Composition for Inducing Differentiation and Protection of Neural Stem Cells and Method for Inducing Neuro-Regeneration Using the Same Composition

ABSTRACT

The present invention relates to a method of inducing neuro-regeneration comprising administering a MEK 1/2 inhibitor to a patient in need thereof. In the present invention, the MEK1/2 inhibitor induces neuro-regeneration by differentiating neural stem cells into neurons, by protecting neural stem cells and neurons against cytotoxicity of amyloid-betas, or by both of the above. Also, the present invention relates to a method of protecting neurons against neuronal loss or damage comprising administering a MEK1/2 inhibitor. In addition, this invention relates to a method of preventing or treating neurodegenerative disease due to neuronal loss or damage for patients in need thereof comprising administering a MEK 1/2 inhibitor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/897,138, filed Feb. 14, 2018, which is a continuation ofInternational Application No. PCT/KR2017/013444, filed Nov. 23, 2017,which claims the right of priority based on Republic of Korea patentapplication no. 10-2017-0036268, filed Mar. 22, 2017, and Republic ofKorea patent application no. 10-2016-0158739, filed Nov. 25, 2016 eachof which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a method of inducing neuro-regenerationcomprising administering a MEK 1/2 inhibitor to a patient in needthereof and to a composition comprising a MEK1/2 inhibitor for use inthe above method. In the present invention, the MEK1/2 inhibitor inducesneuro-regeneration by differentiating neural stem cells into neurons, byprotecting neural stem cells and neurons against cytotoxicity ofamyloid-betas, or by both of the above. Also, the present inventionrelates to a method of protecting neurons against neuronal loss ordamage comprising administering a MEK1/2 inhibitor and to a compositioncomprising a MEK1/2 inhibitor for use in the above method. In addition,this invention relates to a method of preventing or treatingneurodegenerative disease due to neuronal loss or damage for patients inneed thereof comprising administering a MEK 1/2 inhibitor and to thecomposition comprising the MEK1/2 inhibitor for use in the above method.

BACKGROUND ART

Neurodegenerative disease such as Alzheimer's disease (AD) andParkinson's disease (PD) are prevalent in the elderly population and thenumber of patients is increasing exponentially with the aging ofsociety. Moreover, reports of early-onset types of neurodegenerativedisease in the young are not uncommon. Thus, there is great interest indeveloping treatments that help stop the progress of the disease orrecover damaged brain tissues.

The exact causes of such neurodegenerative disease have not beenestablished yet. According to what is known so far, neuronal cells inspecific locations in the brain (e.g. the hippocampus or substantianigra) are damaged leading to a defective neural network among thereduced number of neuronal cells, which results in various symptoms ofthe neurodegenerative disease.

Research is being carried out in various fields to look for treatments.To date, drugs related to the relief of symptoms include memantine (NMDAreceptor antagonist), L-DOPA (dopamine mimic drug), etc. Other drugs arealso limited to a short-term effect or have been found to have sideeffects with continual use, making it difficult to expect them toprovide for treatment beyond the temporary relief of symptoms.Therefore, a fundamental treatment for the cause of neurodegenerativedisease is in great need.

Neural stem cells (NSC) and neural progenitor cells (NPC), cells thatare capable of differentiating into neural cells, are present in theadult brain. Neural stem cells are present in the subventricular zone ofthe lateral ventricle and dentate gyrus of the hippocampus, and it is inthis region that neurogenesis occurs throughout the entire animal's lifethrough differentiation and proliferation of neural stem cells (Zhao etal. (2008) Mechanisms and Functional Implications of Adult Neurogenesis.Cell 132:645-660).

Since brain neuronal cell damage and loss occur in neurodegenerativedisease, replacement of damaged or lost neurons with normal functioningneurons through the stimulation of NSCs and NPCs could be a fundamentaltreatment for neurodegenerative disease. This method of treatmentincludes the method of stem cell treatment, where NSCs and NPCs areisolated from the patient's body, stimulated in vitro to differentiateinto neurons, and then transplanted back into the patients. However,there is difficulty in isolating NSCs and NPCs from patients and thentransplanting them back into patients. Also, the transplanted NSCs andNPCs quickly lose their activity in the brain, requiring repeatedtransplantations. As an alternative, instead of transplanting neuralstem cells into patients, a method of generating neurons in thepatient's brain by stimulating NSCs and NPCs to differentiate with theuse of drugs has recently been proposed (Davies et al. (2015) Stemistry:The Control of Stem Cells in Situ Using Chemistry. J. Med. Chem.58:2863-2894).

Amyloid-beta (Aβ) is a peptide of 36-43 amino acids, which is producedby the cleavage of the amyloid precursor protein (APP), a type 1integral membrane protein, by β-secretase and γ-secretase. Amyloid-beta(Aβ) aggregates as soluble amyloid-beta (Aβ) oligomers and then, viaprotofibrils, forms insoluble Aβ fibrils to eventually accumulate asamyloid plaques in the brain. The deposition of Aβ in the brain isassociated with synapse damage, neuronal damage, and brain atrophy andultimately results in damage in memory and cognitive functions, two verytypical symptoms of Alzheimer's disease (AD). Among the various forms ofAβ, soluble Aβ oligomers, especially trimers and tetramers, are thoughtto be the most toxic forms of Aβ that are associated with neuronaldysfunction and synaptic damage (Murakami, (2014) Conformation-specificantibodies to target amyloid β oligomers and their application toimmunotherapy for Alzheimer's disease. Biosci. Biotechnol. Biochem.78(8):1293-1305; Jana et al. (2016) Membrane-bound tetramer and trimerAβ oligomeric species correlate with toxicity towards cultured neurons.J Neurochem. 136(3):594-608).

Therefore, protecting neurons from Aβ, especially the oligomeric formsof Aβ, is considered the potential target for AD treatment. However, ADpatients have already undergone significant neuronal damage, so inaddition to neuroprotection, neuro-regeneration through thedifferentiation of endogenous neural stem cells is required for thefundamental treatment of AD.

MEK (mitogen-activated protein kinase kinase; also known as MAP2K orMAPKK) is a member of the MAP kinase (mitogen-activated protein kinase;MAPK) signal transduction pathway (written herein as ‘MAPK/ERK pathway’)that follows in the sequence of Ras-Raf-MEK-ERK. When various signalingmolecules such as growth factors, hormones, cytokines, etc., bind tocell membrane receptors and activate receptor tyrosine kinase, theprotein Ras GTPase is activated, which results in the recruitment ofcytoplasmic Raf to the cell membrane. Activated Raf phosphorylates andactivates MEK and ERK, sequentially, and activated ERK in turntranslocates into the nucleus to activate various transcription factors.These transcription factors then bind to the promoters of various genesto control cell proliferation, differentiation, and survival. Becausethe MAPK/ERK signal transduction pathway is hyperactivated in tumorcells, the kinases were seen as important targets to inhibit the diseaseprogress in cancer and other proliferative disease.

There are 7 proteins (MEK1-MEK7) known to be in the MEK family and ofthese, only MEK1 and MEK2 are involved in the signal transduction of theRas-Raf-MEK-ERK pathway. Although MEK1 and MEK2 are encoded by differentgenes, they share high homology (80%) both within the C-terminalcatalytic kinase domains and most of the N-terminal regulatory regions.Although oncogenic forms of MEK1 and MEK2 have not been found in humancancers, it is known that constitutive activation of MEK has been shownto result in cellular transformation. In addition, MEK can also beactivated by other oncogenes. Accordingly, the inhibition of MEK1 andMEK2 has been studied as a target for anticancer drug development. It isunclear, however, what role MEK1 and MEK2 and the MAPK/ERK pathway haveon the proliferation and differentiation of adult neural stem cells.

Furthermore, there are study results that indicate a link between theMAPK/ERK pathway and Aβ or tau proteins in the brain of Alzheimer's (AD)patients. Unfortunately, it is unclear whether AD treatment will requirethe activation or the inhibition of this signaling pathway and whetheror not the control of this signal transduction pathway can be linked toAD treatment.

There are reports of increased levels of expression of proteins in theMAPK/ERK pathway in patients of very early stage Alzheimer's disease(Arendt et al. (1995) Increased Expression and Subcellular Translocationof the Mitogen-Activated Protein Kinase Kinase and Mitogen-ActivatedProtein Kinase in Alzheimer's Disease. Neuroscience 68(1):5-18; Gartneret al. (1999) Elevated Expression of p21ras is an Early Event inAlzheimer's Disease and Precedes Neurofibrillary Degeneration.Neuroscience 91(1);1-5), of the association between ERK1/2 and MEK1/2with the hyperphosphorylation of tau in Alzheimer's patient brain (Peiet al. (2002) Up-Regulation of Mitogen-Activated Protein Kinases ERK1/2and MEK1/2 is Associated with the Progression of NeurofibrillaryDegeneration in Alzheimer's Disease. Brain Res Mol Brain Res.109(1-2):45-55), and of increased Ras expression and ERK1/2 activationin B103 cells (mouse neuroblastoma cells) expressing amyloid precursorprotein (APP) (Chaput et al. (2012) SILAC-based Proteomic Analysis toInvestigated the Impact of Amyloid Precursor Protein Expression inNeuronal-Like B103 Cells. Electrophoresis 33(24):3728-3737).

Meanwhile, other studies have shown that when ERK1/2 is activated,apoptosis induced by Aβ is inhibited and Aβ accumulation decreases(Guerra et al. (2004) Plasma Membrane Oestrogen Receptor MediatesNeuroprotection Against β-Amyloid Toxicity Through Activation ofRaf-1/MEK/ERK Cascade in Septal-Derived Cholinergic SN56 Cells. J.Neurochem. 91:99-109; Watson et al. (2005) Macrophage InflammatoryThrough Activation of Mitogen-Activated Protein Kinase anPhosphatidylinositol 3-Kinase Signaling Pathway. Molecular Pharmacology67(3):757-765; Mills et al. (1997) Regulation of Amyloid PrecursorProtein Catabolism Involves the Mitogen-Activated Protein Kinase SignalTransduction Pathway. J. Neurosci. 17:9415-9422). In addition, it hasbeen reported that ERK1/2 decreases the activity of γ-secretase, whichproduces Aβ from APP, and decreases the expression and activity ofBACE1(β-secretase1) in oxidative stress conditions (Tamagno et al.(2009) JNK and ERK1/2 Pathways Have a Dual Opposite Effect on theExpression of BACE1. Neurobiology of Aging 30:1563-1573).

Therefore, there are conflicting views on the roles of the MAPK/ERKpathway regulation and MEK inhibition in relation to neurodegenerativediseases, such as Alzheimer's disease, which have yet to be clearlyelucidated.

DISCLOSURE OF INVENTION Technical Problem

The inventors of the present invention are to provide a method ofinducing neuro-regeneration by differentiating neural stem cells intoneurons and protecting neural stem cells and neurons from Aβ with acompound inhibiting both MEK1 and MEK2. In addition, the inventors areto provide a method of protecting neurons against neuronal loss ordamage and a method of preventing or treating neurodegenerative diseasedue to neuronal loss or damage with the compound inhibiting both MEK 1and MEK2.

Solution to Problem

The present inventors have discovered that the compound that inhibitsboth MEK1 and MEK2 (herein called “MEK 1/2 inhibitor”), specifically,the compound represented by [Formula 1] can effectively induce thedifferentiation of neural stem cells into neurons; more specifically, itprotects neural stem cells and neurons against amyloid-beta at the sametime it induces the differentiation of neural stem cells into neurons.

One aspect of the present invention relates to the neural stem celldifferentiation-inducing composition comprising the compound of [Formula1]. The composition does not illicit cancerous growth in neural stemcells.

The neural stem cell differentiation-inducing composition induces thedifferentiation of neural stem cells into neurons, even in the presenceof amyloid-beta.

The induction of neuron differentiation by the neural stem celldifferentiation-inducing composition may be the result of inhibition ofboth MEK1 and MEK2.

The present composition may include a specific MEK 1/2 inhibitor otherthan compound of [Formula 1]. This composition induces thedifferentiation of neural stem cells into neurons even in the presenceof amyloid-beta.

Another aspect of the present invention relates to the method ofdifferentiating neural stem cells into neurons using the neural stemcell differentiation-inducing composition.

The differentiation method may consist of treating neural stem cellswith the neural stem cell differentiation-inducing composition andallowing 1 to 7 days for the completion of differentiation.

Another aspect of the present invention relates to the compound of[Formula 1] for use in inducing the differentiation of neural stemcells, specifically for use in the protection of neural stem cells andneurons and differentiation of neural stem cells into neurons even inthe presence of amyloid-beta. Yet another aspect of the presentinvention relates to a specific MEK 1/2 inhibitor for use in inducingthe differentiation of neural stem cells, specifically for use in theprotection of neural stem cells and neurons and differentiation ofneural stem cells into neurons even in the presence of amyloid-beta.

Another aspect of the present invention relates to a kit for use ininducing the differentiation of neural stem cells into neurons in vitro.This kit may include the neural stem cell differentiation-inducingcomposition, culture media, plates, coating solutions, and additivesneeded for culturing cells such as growth factors, etc.

Another aspect of the present invention relates to a method of inducingneuro-regeneration comprising administering a specific MEK 1/2 inhibitorto a patient in need thereof. In the present invention, the MEK 1/2inhibitor induces neuro-regeneration by differentiating neural stemcells into neurons, by protecting neural stem cells and neurons againstcytotoxicity of amyloid-betas, or by both of the above. The mostpreferable MEK 1/2 inhibitor for this method is the compound of [Formula1]. An additional aspect of the present invention relates to thespecific MEK 1/2 inhibitor, specifically the compound of [Formula 1],for use in inducing neuro-regeneration.

Another aspect of the present invention relates to a method ofprotecting neurons against neuronal loss or damage comprisingadministering a specific MEK 1/2 inhibitor to a patient in need thereof.The most preferable MEK 1/2 inhibitor for this method is the compound of[Formula 1]. An additional aspect of the present invention relates tothe specific MEK 1/2 inhibitor, specifically the compound of [Formula1], for use in protecting neurons against neuronal loss or damage.

Another aspect of the present invention relates to a pharmaceuticalcomposition comprising the compound of [Formula 1] as its activeingredient for the prevention or treatment of neurodegenerative diseasesor the method of prevention or treatment of neurodegenerative diseasesusing the compound of [Formula 1].

Neurodegenerative disease pertains to functional disorders in varioussystems such as motor control, cognition, perception, sensory function,and the autonomic nervous system due to the loss or decrease in neuronalfunction. Examples of neurodegenerative diseases include dementia,Alzheimer's disease (AD), vascular dementia, senile dementia,frontotemporal dementia (FTD), Lewy body dementia (LBD), Parkinson'sdisease (PD), multiple system atrophy (MSA), corticobasaldegeneration(CBD), progressive supranuclear palsy (PSP), Huntington'sdisease (HD), amyotrophic lateral sclerosis (ALS, Lou-Gehrig's disease),primary lateral sclerosis (PLS), progressive bulbar palsy (PBP),progressive muscular atrophy (PMA), pseudobulbar palsy, hereditaryspastic paraplegia (HSP), cerebellar ataxia, Creutzfeldt-Jakob disease(CJD), multiple sclerosis (MS), Guillain-Barré syndrome (GBS), etc.

The pharmaceutical composition or method may include or use anotherspecific MEK1/2 inhibitor other than the compound of [Formula 1].

An additional aspect of the present invention relates to the compound of[Formula 1] for use in the prevention and treatment of neurodegenerativedisease. In addition, it relates to the specific MEK 1/2 inhibitor foruse in the prevention and treatment of neurodegenerative disease.

Another aspect of the present invention relates to a method of screeningfor compounds that induce the differentiation of neural stem cells intoneurons and protect them in neurodegenerative disease simulatedenvironments such as Alzheimer's disease. The screening method accordingto the present invention comprises the steps of:

1) treating neural stem cells isolated from adult mouse with neurondamage-inducing substances such as amyloid-beta (specifically in itsoligomeric form), MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine),rotenone, oxidopamine, glutamate, LPS (lipopolysaccharide), S100B (S100calcium-binding protein B);

2) adding a test material to the neural stem cells treated with theabove neuron damage-inducing substances; and

3) examining the differentiation or death of the neural stem cells bymorphology analysis.

In the following, various aspects and embodiments of the presentinvention will be described in detail.

As used herein in the present invention, “neural stem cells” refers tohaving the ability to continually proliferate in the undifferentiatedstate (self-renewal) and the ability to differentiate into variousneurons and glia from one stem cell (multipotency). The neural stem cellis of animal origin. The term animal not only refers to human andprimates, but is intended to include animals such as cows, pigs, sheep,horses, mice, rats, cats, etc., and preferably, humans. In instances,the term “neural stem cell” is used to include “neural progenitor cell”.

As used herein in the present invention, the term “differentiation”refers to the development of a cell into a specialized cell. Morespecifically, it refers to the phenomenon in which the structure orfunction of the cell becomes specialized through cell division,proliferation, and growth of the cell and to the changes in thestructure (morphology) or function of the cells and tissues in order toperform the tasks assigned to them. The differentiation of neural stemcells is preceded by the asymmetric division of the mother cell into twocells that have different properties. One of the daughter cells is thesame as the mother cell, remaining as the stem cell, and the otherdifferentiates into a specialized cell. The fact that this kind ofasymmetric division process accompanies neural stem cell differentiationsignifies that “differentiation of neural stem cell” encompasses themeaning of “proliferation”.

As used herein in the present invention, the term “proliferation” refersto the phenomenon in which a cell divides and proliferates. Thisspecifically refers to the increase in the same type of cells throughcell division, the increase in the number of cells through thereproduction of the exact same form of cells.

As used herein in the present invention, the term “protection” refers topreventing cells from being damaged by harmful external stimuli so thatneural stem cells can proliferate or differentiate without undergoingcell death, and the differentiated neurons can survive in the presenceof cytotoxic factors, specifically, amyloid-beta. In connection to AD,the term “protection” in the present invention includes the aspect thatneural stem cells and neurons are protected against damage caused byamyloid-beta through the lowering of the Aβ(1-42)/Aβ(1-40) ratio in thebrain (Majid et al. (2015) Pharmacologic Treatment with HistoneDeacetylase 6 Inhibitor (ACY-738) Recovers Alzheimer's Disease Phenotypein Amyloid Precursor Protein/Presenilin 1 (APP/PS1) Mice. AlzheimersDement. 170-181; Borchelt et al. (1996) Familial Alzheimer'sDisease-Linked Presenilin 1 Variants Elevate Aβ1-42/1-40 Ratio In Vitroand In Vivo. Neuron. 17:1005-1013).

As used herein in the present invention, the term “prevention” refers toall activities that inhibit or delay the progress of neurodegenerativediseases through the administration of the pharmaceutical compositionaccording to the present invention. “Treatment” refers to all activitiesthat alleviate symptoms or improve the disease state in suspected ordiagnosed neurodegenerative patients.

One aspect of the present invention relates to the neural stem celldifferentiation-inducing composition comprising the compound representedas [Formula 1].

The common name of the compound represented above as [Formula 1] istrametinib and its chemical name isN-(3-{3-cyclopropyl-5-[(2-fluoro-4-iodophenyl)amino]-6,8-dimethyl-2,4,7-trioxo-3,4,6,7-tetrahydropyrido[4,3-d]pyrimidin-1(2H)-yl}phenyl)acetamide.It is disclosed in Example 4-1 of WO2005/121142, the applicant of whichis Japan Tobacco Inc. The compound of [Formula 1] inhibits both MEK1 andMEK2, the upstream components of ERK in the MAPK/ERK (mitogen-activatedprotein kinase/extracellular regulated kinase) signal transductionpathway. This compound is used as a cancer drug for melanoma andnon-small cell cancer. In the present invention, it is used in the formof a free base or a pharmaceutically acceptable salt or solvate.Examples of possible solvates are hydrates, dimethyl sulfoxide, aceticacid, ethanol, nitromethane, chlorobenzene, 1-pentanol, isopropylalcohol, ethylene glycol, 3-methyl-1-butanol, etc.

In particular, one aspect of the present invention relates to acomposition comprising the compound of [Formula 1], which both protectsneural stem cells and neurons and differentiates neural stem cells intoneurons. Amyloid-beta accumulates in the brain as amyloid plaques, isassociated with synaptic damage, neuronal damage, and brain atrophy, andis known to ultimately cause the typical symptoms of Alzheimer'sdisease, memory and cognitive dysfunction. Therefore, protecting neuralstem cells and neurons against amyloid-beta while regenerating neuronsthrough the differentiation of endogenous neural stem cells mayconstitute a fundamental treatment for Alzheimer's disease.

Aβ(1-42) which consists of 42 amino acids has a higher tendency to formaggregates than Aβ(1-40) and a higher tendency to form the more toxictrimers or tetramers and is thus considered to be strongly associatedwith the pathologic state of Alzheimer's disease. Therefore, thecomposition that can protect and differentiate neural stem cells even inthe presence of Aβ(1-42), especially Aβ(1-42) oligomers, is preferable.

As shown in the test examples, with the purpose of finding a compositionthat induces the differentiation of mouse neural stem cells intoneurons, the inventors have confirmed that compound of [Formula 1] isvery effective in inducing the differentiation of neural stem cellsisolated from mouse embryonic or adult brain into neurons.

Neural stem cells have the ability to differentiate into various neuronsor into glia, such as oligodendrocytes, astrocytes, and microglia.Compound of [Formula 1] differentiates neural stem cells mostly intoneurons and limits the differentiation into glia. Therefore, compound of[Formula 1] can effectively induce the generation of neurons(neurogenesis), thereby allowing the replacement of damaged neurons withthese “new” neurons in the brain of neurodegenerative disease patientswith neuronal damage, and can be used as a drug that promotes neuralregeneration or neuro-regeneration.

According to the specific examples of the present invention, theinventors have established through oligomeric Aβ-treated in vitroexperiments that simulate the brain environment of Alzheimer's patientsthat compound of [Formula 1] protects against death of neural stem cellsor neurons, and induces the differentiation of neural stem cells intoneurons (FIG. 2)

Additionally, one aspect of the present invention relates to the neuralstem cell differentiation-inducing composition comprising a specificcompound that inhibits both MEK1 and MEK2. In this invention, thecompound that inhibits both MEK1 and MEK2 is also called “MEK 1/2inhibitor”. “MEK 1/2 inhibitor” preferably has an IC50 value in the nMlevel and a difference of less than 10× in the IC50 values of MEK1 andMEK2, preferably less than 5×. The IC50 for MEK1 and 2 can be measuredby methods in references such as [Yamaguchi et al. (2011) InternationalJournal of Oncology 39:23-31]. The MEK 1/2 inhibitor that may be used inthe present invention is a compound that induces the differentiation ofneural stem cells into neurons while protecting the neural stem cellsand neurons against toxic materials such as Aβ. Examples of MEK 1/2inhibitors that may be used in the present invention are as follows:trametinib, pimasertib(AS703026), AZD8330, binimetinib (MEK162,ARRY-162, ARRY-438162), refametinib (RDEA119, Bay 86-9766), PD318088,PD0325901, RO5126766.

The chemical structure of the preferred MEK 1/2 inhibitors and theirIC50 values and the references describing the methods of measuring theIC50 values are listed as follows:

IC50 value for MEK 1, MEK2 (References for the method of measuring IC50Name Chemical Structure values) Trametinib

0.92~3.4 nM (International Journal of Oncology 2011; 39: 23-31)Pimasertib (AS703026)

≤1 μM (US 2009/0093462, Table I, Example 115) AZD8330

7 nM (AACR Annual Meeting, 2009, Abst 3696) Binimetinib (ARRY-162,ARRY-438162)

12 nM (American College of Rheumatology, 2006 Annual Scientific Meeting,Abst 794) Refametinib (RDEA119, Bay 86-9766)

MEK1: 19 nM, MEK2: 47 nM (Cancer Res. 2009; 69(17): 6839-47) PD318088

1.4 nM (WO 02/06213, Example 40) PD0325901

3.6~24 nM (Oncotarget 2012; 3: 1533- 1545) RO5126766 (CH5126766)

160 nM (Cancer Res. 2013; 73(13): 4050-4060)

In addition, one aspect of the present invention relates to acomposition comprising a MEK 1/2 inhibitor for differentiating theneural stem cells into neurons while protecting neural stem cells andneurons against amyloid-beta, especially the oligomeric Aβ(1-42) form.

Using a selective inhibitor for either MEK1 or MEK2, not the MEK 1/2inhibitor that inhibits both MEK1 and MEK2, is not desirable since itsneural stem cell differentiation- inducing activity is weak. Forexample, cobimetinib is a MEK1-selective inhibitor that shows 100× orgreater selectivity toward MEK1 compared with MEK2 (MEK1 IC50=0.95 nM,MEK2 IC50=199 nM; Molecules 2017;22:1551). Unlike the MEK 1/2 inhibitor,cobimetinib does not induce the differentiation of mouse adult neuralstem cells even at a high concentration of 10 M, regardless of whetheror not amyloid-beta was treated (Example 7).

Also, the fact that inhibition of both MEK1 and MEK2 is involved ininducing NSC differentiation into neurons and protecting NSC and neuronswas confirmed by experiments in Example 5. These experiments used shRNA(short Hairpin RNA) to inhibit MEK1 and MEK2 expression and usedplasmids with constitutively active MEK1 (CAMEK1) and constitutivelyactive MEK2 (CAMEK2) to activate MEK1 and MEK2 expression (Example 5).

However, not all MEK 1/2 inhibitors show the same effect. For example,MEK 1/2 inhibitors U0126, PD184352, and BI847325 showed weak neural stemcell (NSC) to neuron differentiation-inducing effects or causedcytotoxicity, rendering them unsuitable to use as the neural stem celldifferentiation-inducing composition of the present invention (FIG. 10aand FIG. 10c ). Therefore, the NSC to neuron differentiation-inducingactivity or NSC and neuron protection activity can differ depending onthe different unique properties the compound has other than its MEK 1/2inhibiting activity. In the present invention, the MEK 1/2 inhibitorsthat showed NSC to neuron differentiation-inducing activity or NSC andneuron protection activity are trametinib, pimasertib(AS703026),AZD8330, binimetinib, refametinib, PD318088, PD0325901, and R05126766.

In particular, compound of [Formula 1] (trametinib) showed markedlysuperior differentiation and protection against Aβ capabilities evenwhen compared to the other MEK1/2 inhibitors that may be used in thepresent invention. For example, compound of [Formula 1] showed markedlysuperior differentiation and protection against Aβ capabilities comparedwith AS703026 at 100× or greater lower concentration. This effect ofcompound of [Formula 1] is markedly superior to just the predictedeffect of its MEK1/2 inhibitory activity.

Compound of [Formula 1] has never been used for the purpose of inducingthe differentiation of neural stem cells into neurons and has only beenknown as a MEK 1/2 inhibitor that inhibits the activities of both MEK1and MEK2 through ATP non-competitive binding and as melanoma andnon-small cell cancer treatment drugs.

Another aspect of the present invention relates to the method ofinducing the differentiation of NCS into neurons using the compound of[Formula 1] or other MEK1/2 inhibitors.

As for the method disclosed in the present invention, neural stem cellsmay be isolated from embryonic or adult brain according to knownmethods. Alternatively, neural stem cells may be purchased from themarket or may be cultured by any conventional method known in the art.There is no particular restriction as to the above. In the Examplessection that follows, neural stem cells isolated from the frontal lobesof day 14.5 mouse embryos and the subventricular zone of week 8 micewere used.

Before differentiation, the neural stem cells may be inoculated into aculture medium and cultured at 37° C. The culture medium may be anygrowth factor supplemented serum-free medium with no particularrestrictions. The medium may be, for example, Dulbecco's ModifiedEagle's Medium/Nutrient Mixture F12 (DMEM/F12)(1:1) with the addition ofone or more medium components selected from the group consisting of90-110 μM putrescine, 20-40 nM selenite, 10-30 nM progesterone, 1.0-2.0mg/ml d-(+) glucose, 20-30 μg/ml insulin, 0.05-0.2 mg/mlapo-transferrin, 0.3-0.6 mM Glutamax, 50-150 IU/ml penicillin, and50-150 μg/ml streptomycin, and with the further addition of growthfactor selected from the group consisting of 10-30 ng/ml bFGF, 10-30ng/ml EGF, or mixtures thereof.

The neural stem cells may be cultured in growth factor supplemented N2medium [Dulbecco's Modified Eagle's Medium (DMEM/F12 (1:1) supplementedwith 100 μM putrescine, 30 nM selenite, 20 nM progesterone, 1.55 mg/mld-(+)-glucose, 25 μg/ml insulin, 0.1 mg/ml apo-transferrin, 0.5 mMGlutamax, 100 IU/ml penicillin, and 100 μg/ml streptomycin)] to obtainundifferentiated neural stem cells.

The differentiation of cultured neural stem cells into neurons involvesthe treatment of neural stem cells with the differentiation-inducingcomposition comprising the compound of [Formula 1] and then allowing fordifferentiation according to a method known in the art. For example, theneural stem cell differentiation-inducing composition of the presentinvention is added to the medium containing the cultured neural stemcells, and differentiation is induced at 37° C.

Neural stem cells differentiate into neurons through a process ofdifferentiation under the various culture conditions mentioned above(e.g., the contents and quantity of the medium components and theculture period). The culture conditions are not particularly limited tothe conditions mentioned above. Preferably, the culture temperature isfrom 35° C. to 40° C., at which the differentiation of the neural stemcells can be induced. If the culture temperature is lower than 35° C. orexceeds 40° C., the neural stem cells undergo cell death beforedifferentiating into neurons.

Before the neural stem cell differentiation-inducing compositioncomprising the compound of [Formula 1] is added, it is preferable toensure a sufficient concentration of cells in the neural stem cellculture. In addition, to observe changes in the culture such as cellproliferation, differentiation, or death, it is preferable to treat theneural stem cells with the neural stem cell differentiation-inducingcomposition comprising the compound of [Formula 1] by theabove-described method within a culture period of 7 days or less. Tothis end, the culture period of the neural stem cells is preferably atleast 1 day to a maximum of 7 days to ensure a sufficient concentrationof cells.

As for the concentration of the compound of [Formula 1], it ispreferable to add it to the neural stem cells at a concentration of 1 nMto 20 μM. If the concentration is less than 1 nM, the neural stem celldifferentiation-inducing ability is reduced, if it is greater than 20μM, cell cytotoxicity becomes a problem. For the addition of thecompound, neural stem cells are typically seeded into the plate wells tocover up to 70-80% of the surface of the well. For example, 1×105cells/well are seeded into 12 well plates, 5×105 cells/well for 6 wellplates.

Furthermore, as it will be later explained in the Examples section, itis preferable to use the compound of [Formula 1] at a concentration of10 nM to 10 μM, more preferably, 10 nM to 100 nM. If the concentrationis less than 10 nM, the time it takes to induce differentiationincreases, which is uneconomical. However, if it is greater than 10 μM,the compound of [Formula 1] as an active ingredient becomes in excess,and upon subsequent in vivo administration, the inhibition of MEK1 andMEK2 may become too strong, may affect many intracellular signalingpathways, and as a result, may induce many unwanted reactions.

After the addition of the neural stem cell differentiation-inducingcomposition comprising the compound of [Formula 1] which is an inhibitorto both MEK1 and MEK2 to the neural stem cell culture, it takes 1 to 7days, preferably about 3 to 5 days, for the differentiation process tocomplete.

Advantageous Effect of Invention

When the neural stem cell differentiation-inducing composition of thepresent invention is applied to patients with neurodegenerative disease,it induces the neural stem cells in the patient's brain to differentiateinto neurons and allows the replacement of damaged or lost neurons bythe “newly made” neurons. That is, the composition of the presentinvention induces neural regeneration or neuro-regeneration throughneurogenesis from neural stem cells. Therefore, the composition can beused for the prevention or treatment of neurodegenerative diseases. Inthe present invention, “neurogenesis” signifies the generation ofneurons from neural stem cells, and “neural regeneration” or“neuro-regeneration” signifies the organizational and functionalregeneration of the nervous system that was degenerated due to neuronalcell death through neurogenesis. In addition, the composition of thepresent invention can exert a treatment or prevention effect byprotecting neural stem cells or neurons against amyloid-beta oligomers.

Furthermore, applications of the present invention can be widely used asmaterials for the examination of drug effects or for numerous studies inthe development of new drugs for neurodegenerative disease.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is the morphology analysis of Example 1 in which thedifferentiation of mouse embryonic neural stem cells into neurons whentreated with various concentrations of trametinib and pimasertib(AS703026) is observed by phase-contract microscopy. UD and D areundifferentiated mouse embryonic neural stem cells obtained from Example1 Step 1A and differentiated mouse embryonic neural stem cells obtainedfrom Step 1B, respectively, that are not treated with any test material.

FIG. 2 is the morphology analysis of Example 2, where the bottom rowshows the result of mouse adult neural stem cells treated with 10 μMoligomeric amyloid-beta (Aβ1-42) and the top row shows neural stem cellsnot treated with amyloid-beta. UD and D are undifferentiated mouse adultneural stem cells obtained from Example 2 Step 1A and differentiatedmouse adult neural stem cells obtained from Step 1B, respectively, thatare not treated with any test material. Trametinib (10 nM), trametinib(100 nM), memantine (5 μM), memantine (10 μM), and AS703026 (10 μM) arethe results obtained when the undifferentiated mouse adult neural stemcells obtained from Example 2 Step 1A were treated with the respectivetest materials at the respective concentrations.

FIG. 3 is the comparison of cell morphology analysis of mouse embryonic14.5 day neural stem cells that are treated (bottom row) or not treated(top row) with 10 μM oligomeric amyloid-beta according to ComparativeExample 1. UD (undifferentiated) and D (differentiated) areundifferentiated and differentiated mouse embryonic neural stem cellsobtained from Comparative Example 1 Step 1, respectively, that are nottreated with any test material. Trametinib (100 nM), memantine (10 μM),and AS703026 (10 μM) are the results obtained when undifferentiatedmouse embryonic neural stem cells obtained from Comparative Example 1Step 1 were treated with the respective test materials at the respectiveconcentrations.

FIG. 4 is the fluorescent microscopy images of Example 3. In the firstrow, UD and D are undifferentiated and differentiated embryonic neuralstem cells, respectively, not treated with any test material. The secondand third rows are images of cells treated with the respectiveconcentrations of trametinib and AS703026. The blue dots represent cellnuclei stained with DAPI, and the cells with red elongated thin branchesrepresent neurons stained with rhodamine-coupled Tuj1.

FIGS. 5a-5b show the result of Example 4-1 that shows the relative mRNAexpression levels of the neuronal-specific marker Tuj1 (FIG. 5a ) andthe dopaminergic neuronal marker TH (FIG. 5b ) in mouse embryonic neuralstem cells treated with various concentrations of trametinib andAS703026.

FIGS. 6a-6d are part of the result of Example 4-2 that shows therelative mRNA expression levels of the dopaminergic neuronal marker TH(FIG. 6a ), the cholinergic neuronal marker ChAT (FIG. 6b ), the motorneuron marker Isll (FIG. 6c ), and the GABAergic neuronal marker Gad1(FIG. 6d ) in mouse embryonic neural stem cells treated with variousconcentrations of trametinib.

FIGS. 7a-7c are part of the result of Example 4-2 that shows therelative mRNA expression levels of the neuronal marker Tuj1 (FIG. 7a ),the cholinergic neuronal marker ChAT (FIG. 7b ), and the dopaminergicneuronal marker TH (FIG. 7c ) in mouse adult neural stem cells treatedwith 10 nM trametinib (Tra) and 10 μM AS703026 (AS).

FIG. 8a is the result of Example 5-1 that confirms the presence orabsence of expression of the dopaminergic neuronal marker TH throughRT-PCR in order to analyze the ability of mouse embryonic neural stemcells, where MEK1 or both MEK1 and MEK2 expression are inhibited, todifferentiate into neurons.

FIG. 8b is part of the result of Example 5-1 that shows the relativemRNA expression levels of Tuj1 and TH in mouse embryonic neural stemcells where either MEK1 or MEK2 or both MEK1 and MEK2 expression areinhibited by shMEK1 and shMEK2, and confirms the presence or absence ofthe Tuj1 and TH proteins though western blotting.

FIG. 8c is part of the result of Example 5-2 that shows the relativemRNA expression levels of Tuj1 and TH in mouse embryonic neural stemcells where either MEK1 or MEK2 or both MEK1 and MEK2 expression areactivated by CAMEK1 and CAMEK2, and confirms the presence or absence ofthe Tuj1 and TH proteins though western blotting.

FIGS. 9a-9b are the result of Example 5-3 that shows cell morphologyobservations as seen by phase-contrast microscopy (FIG. 9a ) and theanalysis of the relative mRNA expression levels of the neuronal markerTuj1 (FIG. 9b ) in Aβ-treated or non-treated mouse adult neural stemcells where either MEK1 or MEK2 or both MEK1 and MEK2 expression areinhibited by shMEK1 and shMEK2.

FIGS. 10a-10c are the result of Example 6 that shows cell morphologyobservations as seen by phase-contrast microscopy (FIG. 10a ) and therelative mRNA expression level of Tuj1 (FIG. 10b ) in mouse embryonicneural stem cells treated with MEK1/2 inhibitors trametinib, AZD8330,PD184352, refametinib, PD318088, binimetinib, and AS703026 inconcentrations of 0.1 μM, 1.0 μM, and 10 μM. FIG. 10c is thephase-contrast microscopy observations of mouse adult neural stem cellstreated with PD0325901, RO5126766, BI847325, and U0126 (FIG. 10c ).

FIG. 11 is the result of Example 7 that shows cell morphologyobservations as seen by phase-contrast microscopy of Aβ-treated ornon-treated mouse adult neural stem cells that were then subjected totreatment with MEK1/2 inhibitors trametinib (0.1 μM), AS703026 (10 μM),AZD8330 (1 μM), PD318088 (1 μM), binimetinib (10 μM), refametinib (1μM), PD0325901 (10 μM), RO5126766 (10 μM), and cobimetinib (10 μM) whichis known to be a selective inhibitor of MEK1 compared with MEK2. Therows marked with “-” are cells not treated with amyloid-beta and theones marked with “Aβ1-42” are cells treated with 10 μM amyloid-beta.

FIGS. 12a-12b are part of the result of Example 8 that shows NeuNimmunohistochemical staining in slices in the somatosensory cortex oftrametinib-administered 5XFAD mice (FIG. 12a ). FIG. 12b shows thequantitated cell number ratio of NeuN stained cells intrametinib-administered mice compared to controls that were onlyadministered vehicles (FIG. 12b ).

FIGS. 13a-13b are part of the result of Example 8 that shows NeuNimmunohistochemical staining in slices of the motor cortex oftrametinib-administered 5XFAD mice (FIG. 13a ). FIG. 13b shows thequantitated cell number ratio of NeuN stained cells intrametinib-administered mice compared to controls that were onlyadministered vehicles (FIG. 13b ).

FIGS. 14a-14b are part of the result of Example 8 that shows NeuNimmunohistochemical staining in slices of the hippocampal subiculum oftrametinib-administered 5XFAD mice (FIG. 14a ). FIG. 14b shows thequantitated cell number ratio of NeuN stained cells intrametinib-administered mice compared to controls that were onlyadministered vehicles (FIG. 14b ).

FIG. 15 is the result of Example 9-1 that shows Tuj1 immunohistochemicalstaining in slices of the somatosensory cortex oftrametinib-administered 5XFAD mice. In the pictures, the parts markedwith arrows (→) indicate cells stained with Tuj1 and the parts markedwith arrowheads (▾) indicate plaques formed by amyloid-beta aggregation.

FIGS. 16a-16b are the result of Example 9-2 and 9-3 that shows Niss1,NeuN, Dcx and BrdU staining in slices of the hippocampal dentate gyrusof trametinib-administered 5XFAD mice (FIG. 16a ) and the quantificationof BrdU-labeled cells (FIG. 16b ). In FIG. 16a , parts marked witharrows (→) indicate cells stained with Dcx and the parts marked witharrowheads (▾) indicate cells labeled with BrdU.

FIG. 17 is the result of Example 10 that shows TUNEL (Terminaldeoxynucleotidyl transferase dUTP nick end labeling) staining, anindicator of apoptosis, in slices of the hippocampal subiculum andsomatosensory cortex of trametinib-administered 5XFAD mice. Cells in thehippocampal subiculum that have undergone apoptosis and show greenfluorescence are indicated with arrows (→).

FIG. 18 is the result of Example 11 that shows Purkinje Cells throughTuj1 and calbindin staining in slices of the cerebellum oftrametinib-administered 5XFAD mice. Two (Tuj1 staining) or three(calbindin staining) slide pictures of each group are shown.

FIGS. 19a-19b are the result of Example 12 that confirms the presence orabsence of the pERK protein through western blotting using the brainhemispheres of trametinib-administered 5XFAD mice (FIG. 19a ); FIG. 19bis the quantification of the pERK protein levels (FIG. 19b ).

FIG. 20 is the result of Example 13 that shows the quantification ofAβ40 and Aβ42 and the ratio (Aβ42/Aβ40) through ELISA (Enzyme-linkedimmunosorbent assay) using the brain hemispheres oftrametinib-administered 5XFAD mice.

The asterisk (*) marks in the graphs of the Figures indicate thefollowing through statistical t-test results: *: P<0.05, **: P<0.01,***: P<0.005.

BEST MODE FOR CARRYING OUT THE INVENTION

When neural stem cells were treated with the compound of [Formula 1] ofthe present invention, the present inventors saw an increased level ofexpression in the neuronal marker Tuj1, as well as increased levels ofexpression in all of the following: the dopaminergic neuron marker TH,the GABAergic neuron marker Gadl, the motor neuron marker Isl1, and thecholinergic neuron marker ChAT (Example 4). This signifies that thecompound of [Formula1] can differentiate neural stem cells into varioustypes of neurons such as dopaminergic neurons, GABAergic neurons,cholinergic neurons, and motor neurons. Accordingly, the compound of[Formula 1] can be used in the treatment for various neurodegenerativediseases that are caused by various neuronal loss or damage. Forexample, Parkinson's disease is generally associated with the loss ofdopaminergic neurons, motor neuron diseases such as Lou-Gehrig'sdisease/ALS, progressive bulbar palsy (PBP), progressive muscularatrophy (PMA), primary lateral sclerosis (PLS), pseudobulbar palsy(PBA), and hereditary spastic paraplegia (HSP) are associated with theloss of motor neurons, and dementia such as Alzheimer's, vasculardementia, and senile dementia are usually associated with the loss ofcholinergic neurons. In addition, Huntington's disease is usuallyassociated with the loss of GABAergic medium spiny neurons in thestriatum of the basal ganglia.

In particular, because the compound of [Formula 1] allows thedifferentiation of neural stem cells into neurons while protecting themagainst Aβ, the major neuropathological feature of Alzheimer's disease,it can be usefully applied as a treatment for Alzheimer's disease.

The present inventors have confirmed that the compound of [Formula 1]increased the number of neurons in the regions of the subiculum andcerebral cortex layer 5 in the Alzheimer's mouse model (5xFAD) whichexpresses the human Alzheimer's genes (Example 8). The 5xFAD mousecarries the gene mutations for APP (amyloid precursor protein) andpresenilin (PSEN1) which are known to cause human familial Alzheimer'sdisease and accumulates high levels of amyloid deposition in thesubiculum and cerebral cortex layer 5 with concomitant neuronal loss inthese regions. The finding that the compound of [Formula 1] increasedthe number of neurons in the 5xFAD mouse model supports the fact thatthe compound of [Formula 1] induces the differentiation of neural stemcells into neurons in vivo to increase the number of neurons and/orprotects neurons against amyloid-beta.

Also, the compound of [Formula 1] increased the number of neurons invarious regions of the cerebral cortex in the 5xFAD mouse, especiallythe motor cortex and somatosensory cortex regions, when compared withcontrols (Example 8, FIG. 12, 13). This shows that the compound of[Formula 1] can be used for the treatment of motor neuron disease, suchas ALS, caused by loss of neurons in that region.

Also, the compound of [Formula 1] increased axon arborization orpreserved axon structure of the Purkinje Cells in the 5xFAD mousecerebellum when compared with controls (Example 11, FIG. 18). This showsthat the compound of [Formula 1] can be used for the treatment ofcerebellar ataxia caused by the loss or damage of cerebellar PurkinjeCells.

The compound of [Formula 1] generates new neurons (neurogenesis),protects neurons, or does both and through this, has the effect ofinducing neural regeneration or neuro-regeneration. As shown in theresults of Example 9, the compound of [Formula 1] increased theexpression of the neuronal marker Tuj1(marker for neurons in the processof neurogenesis) in the somatosensory cortex region of the Alzheimermodel mouse (5xFAD), increased the number of type 2 or type 3 shapedcells (that appear specifically during neurogenesis) in the subgranularzone (SGZ) of the dentate gyrus (Niss1 and NeuN staining results in FIG.16), and increased the number of immature neuronal cells that expressDCX and dividing cells stained by BrdU (FIG. 16). The results supportthat trametinib induces neurogenesis in the cerebral cortex andhippocampal dentate gyrus of the mouse.

Moreover, the compound of [Formula 1] decreased the number of dyingcells as detected by TUNEL assay in the 5xFAD mouse (Example 10, FIG.17), increased axon arborization or preserved axon structure of thecerebellar Purkinje Cells (Example 11, FIG. 18), and decreased the ratioof Aβ(1-42)/Aβ(1-40) in the 5xFAD mouse brain tissue (Example 13, FIG.20). This shows that the compound of [Formula 1] can play a role inneuro-regeneration by protecting neurons and improving their conditionor activity in an environment where neuronal damage and loss occur.

Accordingly, another aspect of the present invention relates to thepharmaceutical composition comprising the compound of [Formula 1] as anactive ingredient for the prevention and treatment of neurodegenerativedisease, to the method of prevention and treatment for neurodegenerativedisease using the compound of [Formula 1], and to the compound of[Formula 1] for use in the prevention and treatment of neurodegenerativedisease. In the present invention, other MEK1/2 inhibitors thatdifferentiate NSC into neurons while protecting them from toxicsubstances such as Aβ may be used in place of the compound of [Formula1], but it is particularly preferable to use the compound of [Formula1].

As mentioned above, neurodegenerative disease signifies the degenerationof mental and physical function caused by the gradual loss of thestructure and function of neurons. Specifically, it includes disordersselected from dementia, Alzheimer's disease, vascular dementia, seniledementia, frontotemporal dementia, Lewy body dementia, Parkinson'sdisease, multiple system atrophy, corticobasal degeneration, progressivesupranuclear palsy, Huntington's Disease, Lou Gehrig's disease/ALS,primary lateral sclerosis, spinal muscular atrophy, progressive bulbarpalsy (PBP), progressive muscular atrophy (PMA), pseudobulbar palsy,hereditary spastic paraplegia (HSP), cerebellar ataxia,Creutzfeldt-Jakob disease, multiple sclerosis, Guillain-Barre syndrome,etc.

In particular, because the compound of [Formula 1] shows a significantdifferentiation-inducing effect and neuro-protective effect, even atlower concentrations than the previous concentrations used for itsanticancer activity, it can be safely administered at a lower dose thanthat used for cancer treatment. When using the compound of [Formula 1]as a cancer drug, the recommended dose is 2 mg once a day, and if alower dose is required due to side-effects, the dose is reduced to 1.5mg once daily and then to 1 mg once daily. In the present invention, weconfirmed that the compound of [Formula 1] shows neural stem celldifferentiation-inducing activity at a dose as low as 0.1 mg/kg/day in5xFAD mouse experiments. When this dose is converted to adjust for a 60kg person, it translates to 0.48 mg/day (Journal of Basic and ClinicalPharmacy, 7(2), 27-31, 2016).

In the present application, the term ‘comprising as an activeingredient’ indicates including enough of the ingredient to suppress theneurodegenerative disease associated with the present invention.

The preventive or therapeutic composition of the present invention canbe produced into formulations commonly used in the art, for example,oral medication or parenteral medication such as injectables.

The pharmaceutical composition of the present invention can includesuitable carriers, excipients, and diluents commonly used inpharmaceutical preparations and can be formulated in the form of oralformulations such as powder, granules, tablets, capsules, suspensions,emulsions, syrups, aerosols, etc., or topical preparations,suppositories, patches, and sterilized injection solutions.

The carriers, excipients, and diluents that can be included in thecomposition of the present invention are lactose, dextrose, sucrose,sorbitol, mannitol, xylitol, erythritol, maltitol, starch, acaciarubber, alginate, gelatin, calcium phosphate, calcium silicate,cellulose, methyl cellulose, microcrystalline cellulose, croscarmellosesodium, hydroxypropylmethyl cellulose, polyvinlypyrrolidone, water,methyl hydroxybenzoate, propyl hydroxybenzoate, talc, magnesiumstearate, sodium lauryl sulfate, colloidal silicon dioxide,croscarmellose sodium, mineral oil, etc.

Commonly used diluents and excipients such as fillers, extenders,binders, wetting agents, disintegrators, and surfactants are used forpharmaceutical formulations. Solid formulations for oral administrationinclude tablets, pills, powder, granules, capsules, etc. Solidformulation is prepared by adding at least one excipient such as starch,calcium carbonate, sucrose, lactose, or gelatin to the composition ofthe present invention. In addition to simple excipients, lubricants suchas magnesium stearate and talc are also used. Liquid formulations fororal administration include suspension, liquids for internal use,emulsion, syrups, etc., and in addition to the commonly used simplediluents such as water and liquid paraffin, they can include variousexcipients such as wetting agents, sweeteners, fragrances,preservatives, etc. Formulations for parenteral administration includesterilized aqueous solutions, non-aqueous solutions, suspensions,emulsions, freeze-dried formulations, suppositories, and patches. Fornon-aqueous solutions and suspensions, propylene glycol, polyethyleneglycol, vegetable oils such as olive oil, and injectable esters such asethyl oleate can be used. Witepsol, macrogol, Tween 61, cacao butter,lauric butter, glycerogelatin, etc., can be used for the suppositorybase.

The composition of the present invention can be administered eitherorally or parenterally and can be either a systemic or topicaladministration.

The recommended dose of the therapeutic composition of the presentinvention may vary depending on the patient's condition, the patient'sweight, the severity of the disease, form of medication, route ofadministration, period of treatment, etc. and can be accordinglydetermined by those skilled in the art. For example, the composition ofthe present invention can be administered daily at a dose of 0.0001 to10 g/kg, preferably 0.001 to 8 mg/kg. The dosage can be once a day ordivided into several times a day. Preferably, the compound of [Formula1] can be administered at a daily dose ranging from 0.1 mg to 10 mg, 0.1mg to 5 mg, 0.1 mg to 2 mg, 0.1 mg to 1 mg, 0.1 mg to 0.5 mg, 0.25 mg to2 mg, 0.25 mg to 1 mg, 0.25 mg to 0.5 mg, 0.5 mg to 2 mg, 0.5 mg to 1mg. For example, the compound of [Formula 1] can be administered at adaily dose of 0.1 mg, 0.125 mg, 0.25 mg, 0.5 mg, 0.75 mg, 1 mg, 1.5 mg,or 2 mg.

In another aspect of the present invention, the present inventiondiscloses a method of screening for materials that induce thedifferentiation of neural stem cells into neurons while at the same timeprotecting NSCs and neurons in neurodegenerative disease simulatedenvironments such as Alzheimer's. The screening method utilizes neurondamage-inducing substances such as amyloid-beta, MPTP(1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), rotenone, oxidopamine,glutamate, LPS (lipopolysaccharide), and S100B (S100 calcium-bindingprotein B) and neural stem cells derived from the mouse and includes thesteps of:

1) treating neural stem cells isolated from adult mouse with neurondamage-inducing substances such as amyloid-beta, specifically in itsoligomeric form, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine),rotenone, oxidopamine, glutamate, LPS (lipopolysaccharide), and S100B(S100 calcium-binding protein B);

2) adding a test material to the neural stem cells treated with theabove neuron damage-inducing substances; and

3) examining the differentiation or death of the neural stem cells bymorphology analysis.

In the screening method, it is preferable that the neural stem cellsused derive from the mouse. Using neural stem cells from animals such asthe mouse over human neural stem cells has the advantages of easier cellculturing methods and less controversial ethical issues. Human neuralstem cell cultures require frequent culture media replacement andexpensive growth factors, whereas mouse neural stem cell cultures donot. Human neural stem cell cultures require 7 days each for the processof cell expansion and differentiation, whereas mouse neural stem cellcultures require 3-4 days for expansion and only a short period of timefor differentiation, allowing faster speed for screening.

Neural stem cells can be isolated from mouse adult brain and culturedfor use. Mouse adult neural stem cells are isolated from week 8 to week12 mouse, for example, from the sub-ventricular zone of week 8 mouse. Itis common to isolate mouse neural stem cells from the frontal lobes ofmouse embryos that are 12 to 16 days of gestation. Compared to mouseadult neural stem cells, mouse embryonic neural stem cells have astronger stemness, which would make them more likely to withstand toxicenvironments. However, the present inventors observed that when mouseembryonic neural stem cells were treated with amyloid-beta, irrelevantto whether or not the test material was added, all the cells died and noneuronal differentiation could be observed (Comparative Example 1, FIG.3). In contrast, neural stem cells isolated from mouse adult brainsshowed a stronger tolerance to amyloid-beta and was thus considered tobe more suitable for the screening of the neural stem celldifferentiation-inducing material in AD simulated environment.Therefore, we use neural stem cells of the adult mouse for the methodsof the present invention.

The neural stem cells isolated from adult mouse may be inoculated into aculture medium in the undifferentiated state and cultured at 37° C. Theculture medium for the neural stem cells may be any growth factorsupplemented serum-free medium, but it is preferably a growth factorsupplemented IPM medium when first isolating and culturing neural stemcells from adult mouse and then N2 medium when isolating and culturingsingle cells after the formation of neurospheres. The IPM medium is aNeurobasal medium that may include 1-4% B27 supplement, 0.5-2% Glutamax,100 IU/ml penicillin, and 100 μg/ml streptomycin. The N2 medium is aDulbecco's Modified Eagle's Medium/Nutrient Mixture F12 (DMEM/F12)(1:1)that may further contain one or more medium components selected from thegroup consisting of 90-11 μM putrescine, 20-40 nM selenite, 10-30 nMprogesterone, 1.0-2.0 mg/ml d-(+)-glucose, 20-30 μg/ml insulin, 0.05-0.2mg/ml apo-transferrin, 0.3-0.6 mM Glutamax, 50-150 IU/ml penicillin, and50-150 μg/ml streptomycin. The N2 medium may be supplemented with growthfactor selected from the group consisting of 10-30 ng/ml bFGF, 10-30ng/ml EGF, and mixtures thereof. Growth factors play a role inmaintaining the neural stem cells in the undifferentiated state. Inorder to accurately determine the test material's activity on inducingneural stem cell differentiation, the test material should be added toneural stem cells maintained in the undifferentiated state by growthfactors that suppress differentiation.

In the present invention's screening method, commercial amyloid-beta,the one available from Gibco (Waltham, Mass.) for example, can be used.It is preferable to use amyloid-beta of human origin. The most commonforms of amyloid-beta are Aβ(1-40) which consists of 40 amino acids andAβ(1-42) which consists of 42 amino acids. Of the two, Aβ(1-42) has astronger tendency to form aggregates, especially the highly toxictrimers and tetramers, and is thus considered to be more highlycorrelated with the pathological state of Alzheimer's disease (Dahlgrenet al. (2002) Oligomeric and Fibrillar Species of Amyloid-β PeptidesDifferentially Affect Neuronal Viability, J. Biol. Chem.277(35):32046-32053; K. Murakami (2014) Conformation-Specific Antibodiesto Target Amyloid-β Oligomers and Their Application to Immunotherapy forAlzheimer's Disease, Biosci. Biotechnol. Biochem. 78(8): 1293-1305).Therefore, it is preferable to use Aβ(1-42), particularly the oligomericform of Aβ(1-42), in the present invention's screening method.

In the present invention's screening method, the oligomeric form ofamyloid-beta should be oligomers of less than 24, preferably 12 or feweramyloid-beta monomers, more preferably a mixture mainly consisting ofamyloid-beta tetramers and trimers with almost no amyloid-betaprotofibrils or fibrils. The oligomeric form of Aβ(1-42) in the presentinvention can be prepared by the method disclosed in the reference[Dahlgren et al. (2002) Oligomeric and Fibrillar Species of Amyloid-βPeptides Differentially Affect Neuronal Viability, J. Biol. Chem.277(35): 32046-32053]. Specifically, Aβ(1-42) is dissolved inhexafluoroisopropanol (HFIP), dried in a vacuum, and the dried peptideis resuspended in DMSO at a concentration of 5 mM. DMEM/F12 (withoutphenol red) is added and the peptide concentration is adjusted to 100μM, after which it is cultured at 4° C. for 24 hours.

In the present invention's screening method, MPTP is a prodrug for theneurotoxin MPP+ (1-methyl-4-phenylpyridinium). MPP+ causes permanentsymptoms of Parkinson's disease (PD) through the destruction ofdopaminergic neurons in the substantia nigra of the brain.

Rotenone, a substance that causes the degeneration of dopaminergicneurons in the substantia nigra by inhibiting the activity of themitochondrial complex 1 in the cell, is known to produce thepathological features of PD.

Oxidopamine, also called 6-hydroxydopamine (6-OHDA) or2,4,5-trihydroxyphenethylamine, is a neurotoxic compound used byinvestigators to selectively destroy dopaminergic and noradrenergicneurons in the brain. It is thought that oxidopamine enters the neuronthrough the dopaminergic and noradrenergic reuptake transporters. Inorder to selectively damage dopaminergic neurons, it is also used with aselective noradrenergic reuptake inhibitor such as desipramine.

Glutamate acts as the main excitatory neurotransmitter in the centralnervous system (CNS), but is known to damage neurons and cause celldeath when present in high concentrations. The excitotoxicity ofglutamate is not only associated with acute CNS damage such as ischemiaor traumatic brain damage, but also with chronic neurodegenerativedisease such as ALS, multiple sclerosis, PD, etc.

LPS (lipopolysaccharide) is a component of the cell surface of Gramnegative bacteria and the one isolated from Salmonella typhimurium(Sigma, St. Louis, Mo.) may be used, for example. LPS elicits a strongimmune response in animals and causes an inflammatory response byactivating microglia in the nervous system. The secretion ofinflammatory substances due to overactivated microglia can disturb thehomeostasis of the immune system and cause CNS autoimmune diseaserelated neurodegenerative disease such as multiple sclerosis, AD, andPD.

S100B is a calcium-binding protein expressed and secreted by astrocytes.It has neurotrophic activity for the development and maintenance ofneurons and affects normal cognitive functions of the brain. However,abnormally high levels of S100B will activate glia and causeneuroinflammatory responses that are harmful to neurons.

In the present invention's screening method, neural stem cells aretreated with neuron damage-inducing substances such as amyloid-betabefore the addition of the test material. In previously publishedexperiments, neural stem cells were first treated with the testmaterials a certain time before amyloid-beta was added to observe thetest materials' neural protection effect (J. Korean Neurol. Assoc.21(2):174-182, 2003). This method does not reflect the actual treatmentsituation where Alzheimer's patients are administered drugs afteramyloid-beta is already present in their brains. Neural stem cellsshould first be treated with amyloid-beta before the addition of thetest material as performed in the present invention in order to moreclosely simulate the brain environment of Alzheimer's patients at thetime point when treatment is commenced.

The test material is added to the neural stem cells after they aretreated with amyloid- beta and further cultured with the daily additionof growth factors. After treating the neural stem cells with the testmaterial, it can be determined whether or not the test material hasneural stem cell differentiation-inducing activity by a morphologyanalysis at the earliest, 12 hours, and latest, 48-72 hours aftertreatment.

Morphology analysis uses the phase-contrast microscope to observe anddetermine the morphology of the cell. As can be seen in the top part ofFIG. 2 labeled UD (undifferentiated) and D (differentiated),differentiated (D) neural stem cells can be clearly distinguished fromundifferentiated (UD) ones. In undifferentiated cells, cell bodies arewide, the shape of neurites such as axons and dendrites are difficult todiscern, and the total cell number is high since the cells arecontinually dividing. In differentiated cells, cell bodies are small andround, while neurites are thin and extended.

The neural stem cells used in the present invention's screening methodare relatively fragile cells compared to normal or cancer cell lines andrespond sensitively to the toxicity of the test material. If the testmaterial shows cell toxicity, dead cells can be seen in the microscope,making it possible to determine cell toxicity at the same time asdetermining differentiation-inducing activity.

According to the present invention's screening method, materials thathave neural stem cell differentiation-inducing activities can bescreened in an environment that simulates the brain environment of anAlzheimer's patient, especially in which oligomeric forms ofamyloid-beta, the form which is known to be strongly correlated withneuronal loss, are present. This makes the present invention's screeningmethod suitable for the screening of candidate materials that can beused for the fundamental treatment of Alzheimer's disease. In addition,the screening method is convenient in that it allows the determinationof whether or not cells have differentiated by examining cellmorphology, without the need for additional experimental analyses. Also,when neural stem cells are allowed to naturally differentiate in mediawithout growth factors, it takes at least 48 hours, after which thechange in cell morphology can be observed. In the case of cells treatedwith materials that have highly efficient differentiation- inducingactivity, their effect can be observed as early as 12 hours aftertreatment and at latest, 48-72 hours after treatment despite thepresence of growth factors in the cell culture media for suppression ofdifferentiation. In this way, the screening method is fast andefficient, since the toxicity of the test material can also bedetermined at the same time the differentiation-inducing effect is.

In addition, the present invention relates to the kit that can be usedto perform the aforementioned screening method. This kit may includeneural stem cells derived from adult mouse, neuron damage-inducingsubstances such as amyloid-beta, MPTP, rotenone, oxidopamine, glutamate,LPS, or S100B, growth factors, culture media, supplements for cellcultures, and cell culture plates (coated or with separate coatingsolutions).

The present invention will be explained in more detail with reference tothe following examples. However, these examples are not to be construedas limiting or restricting the scope and disclosure of the invention. Itis to be understood that based on the teachings of the present inventionincluding the following examples, those skilled in the art can readilypractice other embodiments of the present invention whose experimentalresults are not explicitly presented. Such modifications and variationsare intended to come within the scope of the appended claims.

EXAMPLES Example 1 The NSC Differentiation-Inducing Ability of theCompound of [Formula 1] in Mouse Embryonic Neural Stem Cells

Step 1: Culturing mouse embryonic neural stem cells

Step 1A: Culturing mouse embryonic neural stem cells in theundifferentiated state

Neural stem cells were isolated from the brain of a day 14.5 mouseembryo, treated with 10 ng/ml human basic fibroblast growth factor(bFGF) (Peprotech, Princeton, NG, cat#.100-18B) and 20 ng/ml humanepidermal growth factor (EGF) (Peprotech, cat#. AF-100-15) in a N2culture medium, and cultured in suspension in a 25 cm2 flask (Nunc,Pittsburgh, Pa.) for 4 days. Formation of neurospheres was observedafter 2 days.

In order to isolate single cells, 6-well plates were prepared the daybefore by treating the wells with 15 μg/ml poly-L-ornithine (Sigma, St.Louis, Mo., cat#.P2533) solution and incubating overnight at 37° C. forcoating. The day of the single cell isolation, poly-L-ornithine solutionwas removed, the plates were washed with PBS three times, and 10 μg/mlfibronectin (Gibco, Waltham, Mass., cat#. 33016015) solution was addedand incubated at 37° C. for 2 hours for coating. When plate preparationwas complete, neurospheres were treated with TryPLE (Gibco cat#.12604013), separated into single cells, and counted and prepared tocomprise 4˜5×105 cells per 200˜300 μl culture solution (N2 culturemedium with 10 ng/ml bFGF and 20 ng/ml EGF). Right before seeding, thecoating solution was suctioned out, and the single cells were uniformlyseeded into the culture plate before the plate dried up. Cells wereallowed to attach to the plates for about 1 minute and after checkingthat cells were sufficiently attached, an additional 1.5 ml of culturemedium (N2 culture medium with 10 ng/ml bFGF and 20 ng/ml EGF) was addedto the cells and cultured in a 37° C. incubator.

The composition of the N2 culture medium is as follows:

Dulbecco's modified Eagle's medium (DMEM)/F12 (1:1) (Gibco, cat#.11320033), 100 μM putrescine (Sigma, cat#. 51799), 30 nM selenite (Sigmacat#. S5261), 20 nM progesterone (Sigma cat#. P0130), 1.55 mg/mld-(+)-glucose (Sigma, cat#. G8270), 25 μg/ml insulin (Gibco, cat#.12585014), 0.1 mg/ml apo-transferrin (Sigma cat#. T1147), 0.5 mMGlutamax (Gibco, cat#. A1286001), 100 IU/ml penicillin (Gibco, cat#.15140122), 100 μg/ml streptomycin (Gibco, cat#. 15140122).

Step 1B: Culturing Neural Stem Cells without Inhibiting Differentiation

Mouse embryonic neural stem cells were cultured in accordance with theprocedure in Step 1A except for the addition of bFGF and EGF when neuralstem cells were separated into single cells and seeded.

Step 2: Addition of Test Material

Various concentrations of the compound of [Formula 1] (hereinafter alsoreferred to as trametinib) (Medchem express, Monmouth Junction, N.J.,cat#. HY-10999A) and AS703026 (pimasertib) (Selleckchem, Houston, Tex.,cat#. S1475) were added daily to mouse embryonic neural stem cellscultured as described in Step 1A and cultured for 4 days.

Step 3: Morphology Analysis

Cell morphology was observed by phase-contrast microscopy after fourdays of culture, and the results are shown in FIG. 1.

In FIG. 1., UD (undifferentiated) is undifferentiated mouse embryonicNSC obtained in Step 1A where the cells are not treated with any testmaterial. D (differentiated) is differentiated mouse embryonic NSCobtained in Step 1B where the cells are not treated with any testmaterial. The undifferentiated NSC of the UD group have wide cellbodies, the neurite shape is hard to distinguish, and the overall cellnumbers are higher compared with the D group due to continuous celldivision. The differentiated cells of the D group have smaller roundcell bodies with elongated thin neurites, making them easilydistinguishable from the UD group cells.

As shown in FIG. 1, the compound of [Formula 1] (trametinib) readilyinduced the differentiation of NSC into neurons at low concentrations of10 nM, 25 nM, and 100 nM (0.1 μM). The AS703026-treated group required1.0 μM, a concentration 100 times higher than that of trametinib, forneuronal differentiation to initiate.

Taken together, these results indicate that the compound of [Formula 1](trametinib) induces the differentiation of NSC into neurons and thiseffect is seen even at very low concentrations (at 10 nM and greater).This suggests that the compound of [Formula 1] can be used for thecomposition and method for differentiation to induce the differentiationof NSC to neurons and for the treatment of neurodegenerative disease.

Example 2 The NSC Differentiation-Inducing Ability of the Compound of[Formula 1] in Mouse Adult NSC (Method of Screening for Substances thatcan Induce the Differentiation of NSC into Neurons while Protecting themat the Same Time) Step 1: Culturing Mouse Adult NSC Step 1A: CulturingMouse Adult NSC in the Undifferentiated State

NSC were isolated from the subventricular zone of week 8 mouse brain,treated with 20 ng/ml human basic fibroblast growth factor (bFGF) and 20ng/ml human epidermal growth factor (EGF) in an IPM medium, and culturedas a suspension in 24-well plates for 7 days. The formation ofneurospheres was observed after 4 days.

Two days before the isolation of single cells, 6-well plates wereprepared by treating the wells with 10 μg/ml poly-L-ornithine solutionand incubating overnight at room temperature for coating. The next day,poly-L-ornithine solution was removed and the plates were washed 3 timeswith sterilized triple distilled water. Next, 0.5 mg/ml laminin (Roche,Upper Bavaria, Germany, cat#. 11243217001) solution was added andincubated overnight at 37° C. for coating. When plate preparation wascomplete, neurospheres were treated with 0.025% Trypsin-EDTA, separatedinto single cells, and counted and prepared to comprise 4˜5×105 cellsper 200˜300 μl culture solution. The culture solution used is N2 culturemedium (supplemented with 20 ng/ml bFGF and 20 ng/ml EGF). Right beforeseeding, the coating solution was suctioned out, and the single cellswere uniformly seeded into the culture plate before the plate dried up.Cells were allowed to attach to the plates for about one minute, andafter checking that cells were sufficiently attached, an additional 1.5ml of culture medium (N2 culture medium with 20 ng/ml bFGF and 20 ng/mlEGF) was added to the cells and cultured in a 37° C. incubator for 24hours.

The compositions of the 1PM and N2 culture medium are as follows:

IPM medium: Neurobasal medium (Gibco, cat#. 21103049), B27 supplement(Gibco, cat#. A3582801), Glutamax, 100 IU/ml penicillin, 100 μg/mlstreptomycin.

N2 medium: Dulbecco's modified Eagle's medium (DMEM)/F12 (1:1), 100 μMputrescine, 30 nM selenite, 20 nM progesterone, 1.55 mg/mld-(+)-glucose, 25 μg/ml insulin, 0.1 mg/ml apo-transferrin, 0.5 mMGlutamax, 100 IU/ml penicillin, 100 μg/ml streptomycin.

Step 1B: Culturing Neural Stem Cells without Inhibiting Differentiation

Mouse adult neural stem cells were cultured in accordance with theprocedure in Step 1A except for the addition of bFGF and EGF when neuralstem cells were separated into single cells and seeded.

Step 2: Amyloid-Beta Treatment

After changing the medium of the cultured NSC in Step 1, each well wastreated with 10 μM amyloid-beta (Aβ) (Gibco, cat#. 03112). Wells nottreated with amyloid-beta were left to use as negative controls.

Gibco's (Waltham, Mass.) human Aβ (1-42) was purchased to use for theamyloid-beta (Aβ), and the following process was followed to createoligomers. First, amyloid-beta was dissolved in 100% HFIP(1,1,1,3,3,3-hexafluoro-2-propanol) (Sigma, cat#.105228) to obtain aconcentration of 1 mg/ml and vortexed at room temperature for 1 hour.Then, it was dried for 10 minutes in a speed Vac, after which DMSO(Sigma, cat#.D2650) was added to bring the concentration to 5 mM andthen lightly vortexed at room temperature for 10 minutes. DMEM/F12(without phenol red) (Gibco, cat#. 21041025) was added for a finalconcentration of 100 μM. The solution was incubated at 4° C. for 24hours and then added into the cultured cells.

Step 3: Addition of Test Material

Immediately following treatment with amyloid-beta, 10 nM, 100 nMtrametinib, 5 μM, 10 μM memantine (Sigma, cat#. M9292), and 10 μMAS703026 (pimasertib) were added to the cell cultures. The NCSs werecultured with the daily addition of EGF, bFGF, amyloid-beta, and testmaterials for 4 days.

Step 4: Morphology Analysis

Cell morphology was observed by phase-contrast microscopy after fourdays of culture, and the results are shown in FIG. 2.

In FIG. 2., the top row is mouse adult NSC not treated with amyloid-betaand the bottom row is NSC treated with 10 μM amyloid-beta. UD(undifferentiated) is undifferentiated mouse adult NSC obtained in Step1A where the cells are not treated with any test material. D(differentiated) is differentiated mouse adult NSC obtained in Step 1Bwhere the cells are not treated with any test material. Of the top Aβnon-treated group, the undifferentiated NSC of the UD group have widecell bodies, the neurite shape is hard to distinguish, and the overallcell numbers are higher compared with the D group due to continuous celldivision. The differentiated cells of the D group have smaller roundcell bodies with elongated thin neurites, making them easilydistinguishable from the UD group cells.

The trametinib-treated group readily induced the differentiation of NSCinto neurons at low concentrations of 10 nM and 100 nM, regardless ofwhether or not amyloid-beta was treated. The AS703026-treated grouprequired a much higher concentration than that of trametinib, 10 μM, forneuronal differentiation, regardless of whether or not amyloid-beta wastreated. Both materials did not elicit cell toxicity at theseconcentrations, confirming that they are suitable candidates forAlzheimer's disease (AD).

Moreover, in the group treated with memantine, a drug currently used forthe relief of AD symptoms, the differentiation of NSC into neurons wasnot observed, but rather the opposite, the death of neural stem cells,was observed. Memantine is an NMDA receptor antagonist involved inglutamate signal transduction and works to help normalize neuronalsignal transduction in AD patients. This kind of mechanism does notprovide a fundamental treatment for AD through the recover of damagedneurons. The finding that memantine does not induce differentiation ofNSC but rather causes cell death confirms that it cannot be used as afundamental treatment for dementia.

Comparative Example 1 Effect of Amyloid-Beta Treatment on MouseEmbryonic Neural Stem Cells Step 1: Culturing Mouse Embryonic NSC

Cells were cultured as described in Example 1, Step 1A and 1B.

Step 2: Treatment with Amyloid-Beta

Mouse embryonic NSCs cultured as described in the above Step 1 weretreated with amyloid-beta using the same method as Example 2, Step 2.

Step 3: Addition of Test Material

Immediately following treatment with amyloid-beta, 100 nM trametinib, 10μM memantine, and 10 μM AS703026 (pimasertib) were added. The NCS werecultured with the daily addition of EGF, bFGF, amyloid-beta, and testmaterials for 4 days.

Step 4: Morphology Analysis

Cell morphology was observed by phase-contrast microscopy after fourdays of culture, and the results are shown in FIG. 3.

In FIG. 3., the top row is mouse embryonic NSC not treated withamyloid-beta and the bottom row is NSC treated with amyloid-beta. UD(undifferentiated) is undifferentiated mouse embryonic NSC (not treatedwith any test material) and D (differentiated) is differentiated mouseembryonic NSC (not treated with any test material). In the Aβ-treatedgroup, all the cells died, regardless of whether or not the testmaterials were added, and hence, the effect of the test materials couldnot be determined.

Example 3 Immunocytochemistry Analysis

In order to reconfirm the differentiation of NSC into neurons in Example1, immunocytochemical staining of Tuj1 and DAPI(4′,6-diamidino-2-phenylindole) markers was performed. Tuj1 (Neuronspecific class III beta-tubulin) is a neuron specific marker protein,which was conjugated to rhodamine to show fluorescent red, while DAPIbinds to the cell DNA and stains the cell nuclei fluorescent blue.

Embryonic NSCs cultured as described in Example 1 were seeded into24-well plates with coverslips and treated with trametinib and AS703026in the respective concentrations for 4 consecutive days. The medium wasremoved and the cells were washed with PBS. After fixing with 10%formaldehyde (Sigma cat#. HT501128) at room temperature for 10 minutes,they were washed again with PBS. They were permeabilized with 0.2%Triton X-100 (Sigma, cat#. 93443) at room temperature for 15 minutes,washed with PBS, and incubated with 10% BSA (Sigma, cat#. A2153)+1%normal goat serum (Vector lab, Burlingame, Calif., cat#. S1000) at roomtemperature for 1 hour. Anti-Tuj1 antibody (Cell signaling, Danvers,Mass., cat#. 4466) was diluted in 1% BSA+1% normal goat serum at a ratioof 1:200 and added to the cells and incubated at 4° C. overnight. Thesolution was removed, washed with PBS, and incubated at room temperaturefor 1 hour with the secondary antibody (rhodamine-conjugated antibody)diluted in 1% BSA+1% normal goat serum at a ratio of 1:200. Then, thecells were washed with PBS, incubated with 5 μg/ml DAPI (Sigma, cat#.D9542) for 5 minutes, washed with PBS again, and mounted on a slideglass for analysis with a fluorescent microscope. The results are shownin FIG. 4. As seen in FIG. 4, the group treated with 1.0 μM AS703026showed images of red thin elongated neurites, indicating that neurondifferentiation occurs at this concentration, albeit only to a marginalextent. At concentrations lower than this (0.1 μM), no differentiationwas observed.

In contrast, the group treated with trametinib, even at a very lowconcentration of 10 nM, showed increasingly active differentiationactivity. As for the morphology of the cells, an increasing number ofneurons showing elongated neurites are visible in 10 nMtrametinib-treated cells.

Example 4 Analysis of the Relative Levels of mRNA Expression Example 4-1Analysis of Tuj1 and TH mRNA Expression Induced by the Compound of[Formula 1] in Mouse Embryonic NSC

In order to determine what type of cells the NSCs differentiated into inExample 1, mRNA expression of the neuron specific marker Tuj1 and thedopaminergic neuron marker TH (tyrosine hydroxylase) was analyzedthrough quantitative RT-PCR (qRT-PCR).

Step 1: RNA Isolation

After completing the morphology analysis in Example 1, the medium ofeach treated group of cells was removed and TRIzol® (Invitrogen,Waltham, Mass.) was added to the plate and incubated for 5 minutes atroom temperature to facilitate cell lysis. The cell lysates, togetherwith TRIzol, were transferred to a tube, mixed thoroughly withchloroform (Sigma, cat#. 366919), centrifuged, and the supernatanttransferred to a new tube. Isopropanol (Ducsan, GyunggiDo, Korea, cat#.67-63-0) was added and mixed for RNA isolation, then centrifuged againto remove the supernatant and obtain the pellet. The RNA pellet wasresuspended in 75% ethanol (Ducsan, cat#. 64-17-15), centrifuged, andthe supernatant removed. The pellet was then resuspended in sterilizedtriple distilled water to obtain the mRNA, incubated for 10 minutes at55° C., and stored at −80° C.

Step 2. Reverse Transcription

After measuring the RNA concentration, each group of RNA was adjusted to2 μg and the experiment was performed using a reverse transcription kit(Invitrogen, cat#. 28025013). Sterilized triple distilled water, 1 pMoligo dT, and 1 mM dNTP were added to the RNA and incubated for 5minutes at 65° C. This was followed by the addition of 5X First-strandbuffer, 10 mM DTT, and M-MLV reverse transcriptase and incubated at 42°C. for 1 hour, then at 72° C. for 15 minutes, and at 4° C. for 30minutes. The synthesized cDNA was stored at −20° C.

Step 3: qRT-PCR

PCR was performed by mixing 1 μl cDNA (synthesized above), 1 pM primer,triple distilled water, and Rotor-Gene SYBR® Green (Qiagen, Venlo,Netherlands, cat#. 204074) and using the Rotor-Gene Q (Qiagen). Theprimers (Bioneer, Daej eon, Korea) used are shown in Table 2.

TABLE 2 Gene Forward Primer Reverse Primer GAPDH 5′-CGTGCCGCCTGGAGA5′-TGGAAGAGTGGGAGTTGCTG AACC-3′ TTG-3′ Tuj1 5′-GGTCTGGCGCCTTTG5′-CACCACTCTGACCAAAGATA GA-3′ AAGTTG-3′ TH 5′-AGGTATACGCCACGC5′-CTCGGGTGAGTGCATAGGTG-3′ TGAAG-3′

The results are shown in FIG. 5. FIG. 5a, 5b are the average values ofthe relative mRNA expression levels for each group after 3 rounds ofexperiments. The term relative mRNA expression level signifies that inorder to normalize each group's total RNA level, the mRNA expressionlevel of each differentiation marker is divided by the expression levelof GAPDH whose expression level is fairly constant across cells, andthen the values of each test material are compared with those of thecontrols (undifferentiated NSC) in each group.

As shown in FIG. 5, the trametinib-treated group showed high levels ofexpression of the neuron specific marker Tuj1 and the dopaminergicneuron marker TH at concentrations of 10 nM, 25 nM, and 100 nM. Thisresult indicates that trametinib efficiently induces the differentiationof NSC into neurons, especially into dopaminergic neurons. In addition,trametinib exerted its differentiation-inducing effect at a very lowconcentration of 1 nM. This suggests that the composition according tothe present invention can be used for the treatment of neurodegenerativedisease.

10 μM (10000 nM) AS703026 yielded results comparable to those of 25 nMtrametinib, indicating that trametinib induces differentiation of NSCinto neurons at 400 times (or more) lower concentration than that ofAS703026.

Example 4-2 Analysis of TH, ChAT, Isl1, and Gad1 mRNA Expression Inducedby the Compound of [Formula 1] in Mouse Embryonic and Adult NSC

In order to determine if the compound of [Formula 1] induces thedifferentiation of NSC into cell types other than dopaminergic neurons,mRNA expression of the cholinergic neuron marker ChAT (cholineacetyltransferase), the motor neuron marker Isl1 (Islet1), and theGABAergic neuron marker Gad1 (glutamate decarboxylase 1) was determinedthrough qRT-PCR.

Neural stem cells were cultured as described in Example 1 and after theaddition of 1 nM, 10 nM, 25 nM, and 100 nM trametinib for 2 days, RNAwas isolated and examined for the differentiation markers. mRNAexpression was determined by the same method as in Example 4-1, and theprimers used are shown in Table 3.

The results are shown in FIG. 6.

TABLE 3 Gene Forward Primer Reverse Primer GAPDH 5′-CGTGCCGCCTGGAGAAAC5′-TGGAAGAGTGGGAGTTGC C-3′ TGTTG-3′ Tuj1 5′-GGTCTGGCGCCTTTGGA-3′5′-CACCACTCTGACCAAAGA TAAAGTTG-3′ TH 5′-AGGTATACGCCACGCTGA5′-CTCGGGTGAGTGCATAGG AG-3′ TG-3′ ChAT 5′-CCTGCCAGTCAACTCTAG5′-TACAGAGAGGCTGCCCTG CC-3′ AG-3′ Gad1 5′-TCATGTTATGGAAATCTT5′-CGAGTCACAGAGATTGGT GCTTCAG-3′ CATATACTACT-3′ Isl15′-CGGAGAGACATGATGGTG 5′-GGCTGATCTATGTCGCTT GT-3′ TGC-3′

As shown in FIG. 6, the expression of all the tested neuron markers,dopaminergic neuron marker TH, cholinergic neuron marker ChAT, motorneuron marker Isl1, and GABAergic neuron marker Gad1, increased with theincrease in concentration of the trametinib added. This suggests thattrametinib can be used in the treatment of neurodegenerative diseasethat is caused by various types of neuronal damage.

In order to determine if the same effect takes place in mouse adult NSC,10 nM trametinib and 10 μM AS703026 were each added for 2 days to themouse adult NSC cultured as described in Example 2, Step 1A, and themRNA expression levels of the neuronal marker Tuj1, dopaminergic neuronmarker TH, and cholinergic neuron marker ChAT were analyzed by qRT-PCR.

This result is shown in FIG. 7. Trametinib increased the expression ofTuj1, TH, and ChAT in adult NSC as it did in embryonic NSC. It isnoteworthy that trametinib exhibited a stronger NSC to neurondifferentiation-inducing effect at 1000 times lower concentration thanAS703026.

Example 5 Examination of the NSC Differentiation-Inducing Abilitythrough the Control of MEK1 and MEK2 Expression in Neural Stem CellsExample 5-1 Inhibition of MEK1, MEK2 Expression in Mouse EmbryonicNeural Stem Cells

The NSC to neuron differentiation-inducing ability in relation to theexpression levels of MEK1 and MEK2 was examined. The following methodwas used to produce cells where MEK1 and MEK2 expression is controlled.

First, in order to produce NSCs where MEK1 and MEK2 expression isinhibited, the respective shRNAs that inhibit the expression of MEK1 andMEK2 were used. Specifically, mouse embryonic NSCs cultured as describedin Example 1, Step 1A were seeded into plates and cultured for 24 hours.Then 1 μg/ml shRNA-MEK1(CCGGGCCATCCAACATTCTAGTGAACTCGAGTTCACTAGAATGTTGGATG GCTTTTT) orshRNA-MEK2 (CCGGCCTCCGAGAGAAGCACCAGATCTCGAGATCTGGTGCTTCTCTCGGA GGTTTTTG)were transfected into the cells using lipofectamine (Invitrogen, cat#.18324010) to create NSCs where the expression of either MEK1 or MEK2 orboth are inhibited.

After 4 hours, the culture medium of these transfected cells wasreplaced with N2 culture medium, cultured for an additional 4 days, andthen RNA was extracted using the method in Example 4-1. The NSC toneuron differentiation-inducing ability was analyzed by reversetranscription PCR (RT-PCR). Specifically, RNA was converted to cDNAthrough reverse transcription, and then EX-Taq DNA polymerase (SG Bio,Kyunggi Do, Korea) and primer were added to perform PCR in the T100TMThermal Cycler (Bio-rad, Hercules, Calif.). PCR was performed byincubating at 95° C. for 5 minutes, then repeating 25-35 cycles ofreaction where 1 cycle consists of incubating at 95° C. for 30 seconds,at 55˜62° C. for 30 seconds, and at 72° C. for 30 seconds. The PCRresults were examined by performing gel electrophoresis on 2% agarosegel, which was then analyzed by an image analyzer, LAS-3000 (Fujifilm,Tokyo, Japan).

The primers used for RT-PCR and qRT-PCR in the present Example as wellas Example 5-2 and 5-3 are shown in Table 4.

TABLE 4 Gene Forward Primer Reverse Primer GAPDH 5′-CGTGCCGCCTGGAGAA5′-TGGAAGAGTGGGAGTTGCTGTT ACC-3′ G-3′ Tuj1 5′-GGTCTGGCGCCTTTGG5′-CACCACTCTGACCAAAGATAAA A-3′ GTTG-3′ TH 5′-AGGTATACGCCACGCT5′-CTCGGGTGAGTGCATAGGTG-3′ GAAG-3′ MEK1 5′-CGGCGGTTAACGGGAC5′-GGATTGCGGGTTTGATCTC CA-34′ CA-3′ MEK2 5′-CCTGGATGAGCAGCAA5′-CAGTGAGCCACCATCCATGT-3′ AGGA-3′

The results are shown in FIG. 8a . As shown in FIG. 8a , expression ofthe dopamine neuron marker TH is significantly increased in the NSCwhere both MEK1 and MEK2 are inhibited by the transfection of bothshMEK1 and shMEK2 (shMEK1+, shMEK2+) in comparison to NSC where onlyMEK2 expression is inhibited (shMEK1−, shMEK2+).

In order to examine once more the effect of inhibiting only MEK1 or MEK2or inhibiting both MEK1 and MEK2, the NSC to neurondifferentiation-inducing effect was examined by qRT-PCR and westernblotting. NSC where only MEK1 or MEK2 are inhibited and NSC where bothMEK1 and MEK2 are inhibited were produced with the aforementionedmethods. After 4 hours, the culture medium of the transfected cells wasreplaced with N2 culture medium, cultured for an additional 4 days, andqRT-PCR performed using the method in Example 4-1. The results are shownin the graph of FIG. 8b . As shown in the graph of FIG. 8b , expressionof the neuron markers Tuj1 and TH is significantly increased when bothMEK1 and MEK2 expression is inhibited compared with when only MEK1 orMEK2 is.

Western blotting was performed to examine if the NSC to neurondifferentiation-inducing effect is seen with the inhibition of MEK1 andMEK2 expression, not only in mRNA but also in protein levels.

Western blotting was performed on each group of cells by the followingmethod: After culturing the NSC where MEK1 and MEK2 expression isinhibited for 4 days, medium was removed, RIPA buffer (0.05 M Tris HClpH7.4 (Sigma, cat#.T3253), 0.15 M NaCl (Ducsan, cat#. 7647-14-5), 0.25%deoxycholic acid (Sigma, cat#.D6750), 1% NP-40 (USB, Waltham, Mass.,cat#.19628), 1 mM EDTA (Sigma, cat#.EDS), 1 mM PMSF (Acros organics,Geel, Belgium, cat#. 215740050), 1 mM sodium orthovanadate (Bio labs,Ipswich, Mass., cat#. P0758L), 1 mM sodium fluoride (Sigma, cat#.S7920),protease inhibitors (Sigma, cat#.P83430)) was added into the plate onice, and cells were collected with a scrapper. After incubation on icefor 10 minutes, the supernatant was collected after centrifugation at13000 rpm at 4° C. The protein concentration was measured, sample buffer(0.25 M Tris-HCl pH6.8, 0.05% SDS (Amersco, Solon, Ohio, cat#. 227), 50%glycerol (Ducsan, cat#. 56-81-5), 0.25 M DTT (Invitrogen, cat#.R0861),0.5 mg/ml BPB (Bio-rad, Hercules, Calif., cat#.161-0404) was added, andthe sample was boiled at 100° C. for 10 minutes and then stored at −20°C.

10˜20 μg protein samples were loaded onto 8˜12% SDS-PAGE gel, separated,and transferred to a nitrocellulose membrane, which was then blockedwith 5% skim milk at room temperature for 1 hour. Antibodies againstTuj1, TH (Cell signaling, cat#. 2792), MEK1/2 (Santa Cruz, Dallas, Tex.,cat#. Sc-292838), and ERK (Santa Cruz, cat#. Sc-135900) were eachprepared in 0.1% Tween 20 (Sigma, cat#. P1379) containing tris bufferedsaline (TBS) and incubated with the membrane at room temperature for 2hours or at 4° C. overnight, after which it was incubated with ahorseradish peroxidase-conjugated secondary antibody at room temperaturefor 1 hour. Protein expression was detected with a photosensitiveequipment and the result is shown in the bottom picture of FIG. 8b . Asshown in FIG. 8b , the expression levels of both mRNA and proteins inthe neuron marker Tuj1 and dopamine neuron marker TH significantlyincreased in NSC where MEK1 and MEK2 expression are both inhibited bythe use of both shMEK1 and shMEK2 (shMEK1+, shMEK2+).

In contrast, in the case of NSC where only one of MEK1 or MEK2expression is inhibited, a lower level of expression of Tuj1 and TH isseen compared with that of NSC with both MEK1 and MEK2 inhibition.

Example 5-2 Inducing Expression of CAMEK1 and CAMEK2 in Mouse EmbryonicNeural Stem Cells

In order to examine the NSC to neuron differentiation-inducing effect inrelation to the activation of MEK1 and MEK2, a constitutively activeMEK1 (CAMEK1) plasmid and constitutively active MEK2 (CAMEK2) plasmidthat have mutations for the constitutive expression of MEK1 and MEK2,respectively, were used in the experiments. Specifically, mouseembryonic NSC cultured as described in Example 1, Step 1A were seededinto plates and incubated for 24 hours. Then, 1 μg/ml CAMEK1 and CAMEK2were transfected into the cells using lipofectamine to create NSC wherethe expression of either CAMEK1 or CAMEK2 or both are expressed. After 4hours, the culture medium of these transfected cells was replaced withN2 culture medium that does not contain EGF or bFGF, cultured for anadditional 4 days, RNA and protein were extracted, and quantitativeRT-PCR (qRT-PCR) and western blotting were performed. Through theseexperiments, the effect of MEK1 and MEK2 activation on the NSC to neurondifferentiation-inducing effect was examined and shown in FIG. 8 c.

In contrast to FIG. 8b , FIG. 8c shows that when MEK1 and MEK2 areactivated in an otherwise differentiation-inducing environment,differentiation of the NCS are inhibited. mRNA and protein expression ofthe neuron marker Tuj1 and the dopaminergic neuron marker TH were shownto be inhibited by qRT-PCR and western blotting. The expression of Tuj1and TH was significantly lower in the case of both MEK1 and MEK2activation in comparison with only one of them being activated.

Example 5-3 Inhibition of MEK1 and MEK2 in Mouse Adult Neural Stem Cells

The following experiments were performed to determine if the inhibitionof MEK1 and MEK2 induces the differentiation of NSC in mouse adult NSCand if the effect is the same in conditions where amyloid-beta ispresent.

Mouse adult NSCs cultured as described in Example 2, Step 1A were seededinto plates and cultured for 24 hours. Then 1μg/ml shRNA-MEK1(CCGGGCCATCCAACATTCTAGTGAACTCGAGTTCACTAGAATGTTGGATG GCTTTTT) orshRNA-MEK2 (CCGGCCTCCGAGAGAAGCACCAGATCTCGAGATCTGGTGCTTCTCTCGGA GGTTTTTG)were transfected into the cells using lipofectamine (Invitrogen) tocreate NSC where the expression of either MEK1 or MEK2 or both areinhibited.

After 4 hours, the culture medium of these transfected cells wasreplaced with N2 culture medium or N2 medium treated with 10 μMamyloid-beta, cultured for an additional 2 days, and cell morphologyobserved under a microscope. RNA was extracted using the method inExample 4, qRT-PCR was performed, and the NSC to neurondifferentiation-inducing effect was analyzed.

The result is shown in FIG. 9.

As shown in FIG. 9a , differentiation was more readily induced in NSCwhere both MEK1 and MEK2 expression was inhibited by the transfection ofboth shMEK1 and shMEK2 than in NSC where only one of shMEK1 or shMEK2was transfected.

In the case of Aβ-treated cells, cells died in the group where both MEK1and MEK2 were not inhibited, but in the group where either MEK1 or MEK2or both MEK1 and MEK2 were inhibited, cell death did not occur butinduction of differentiation did.

Also, as shown in FIG. 9b , expression of the neuronal marker Tuj1 wassignificantly increased in the NSC where both MEK1 and MEK2 expressionwas inhibited by the treatment of both shMEK1 and shMEK2(shMEKl+shMEK2). In contrast, in NSCs where the expression of eitherMEK1 or MEK2 was inhibited (shMEK1, shMEK2), expression of the neuronmarker Tuj1 was low as was the NSC to neuron differentiation-inducingeffect compared to the case where both MEK1 and MEK2 were inhibited. Inthe case of Aβ-treated cells, some protective anddifferentiation-inducing effect was seen in NSCs where either MEK1 orMEK2 was inhibited, but in the NSC where both MEK1 and MEK2 expressionwas inhibited, the protective and differentiation-inducing effect wassignificantly higher.

From these results, it is revealed that the inhibition of MEK1 and MEK2in adult NSC not only induces the differentiation of NSC, but alsodemonstrates a protective effect against amyloid-beta.

Example 6 NSC Differentiation-Inducing Effect of Other MEK1/2 Inhibitors

In order to test if other MEK 1/2 inhibitors besides trametinibdemonstrate a NSC differentiation-inducing and protective effect, mouseembryonic NSCs were treated with each of the test material.Specifically, mouse embryonic NSCs cultured as described in Example 1,Step 1A were treated with the respective MEK1/2 inhibitors AZD8330(Selleckchem, cat#. 2134), PD184352 (Selleckchem, cat#. S1020),refametinib (Selleckchem, cat#. S1089), PD318088 (Selleckchem, cat#.S1568), binimetinib (Selleckchem, cat#. S7007), and AS703026 atconcentrations of 0.1 μM, 1.0 μM, and10 μM and incubated. Forcomparison, NSCs were also treated with trametinib at the sameconcentrations. On day 2 of culture, cell morphology was observed byphase-contrast microscopy and the results are shown in FIG. 10a . FIG.10b is the analysis of Tuj1 mRNA expression in the cells of each group.

As shown in FIGS. 10a and 10b , AZD8330, refametinib, PD318088,binimetinib, and AS703026 all induced differentiation, albeit startingat different concentrations. AZD8330, refametinib, and PD318088exhibited differentiation morphology starting at 1.0 μM, whilebinimetinib and AS703026 started at 10 μM. Examining the expression ofthe neuronal differentiation marker Tuj1 by RT-PCR also showed that theyinduce differentiation at the same concentrations. Trametinib showed anexcellent NSC differentiation-inducing effect compared with othercompounds, even at a low concentration of 0.1 μM. In contrast, PD184352showed only a weak NSC differentiation-inducing effect at 0.1 μM, and at1.0 μM and 10 μM, all the cells died.

In addition, mouse adult NSCs cultured as in Example 2, Step 1A weretreated with other MEK 1/2 inhibitors PD0325901 (Selleckchem, cat#.S1036), R05126766 (Selleckchem, cat#. S7170), BI847325 (Selleckchem,cat#. S7843), and U0126 (A.G. Scientific, San Diego, Calif., cat#.U-102) at various concentrations, and their NSC differentiation-inducingeffects were examined. After treatment with the test materials, cellmorphology was observed by phase-contrast microscopy on day 2 ofculture. The results are shown in FIG. 10c . As shown in FIG. 10c ,PD0325901 showed a differentiation-inducing effect starting at 0.1 μM,RO5126766 at 1.0 μM. PD0325901, in particular, showed an excellentinducing effect as it induced differentiation over a wide range ofconcentrations, from 0.1 μM to 10 μM. In contrast, BI847325 showed onlya weak differentiation-inducing effect at 0.1 μM, and at 1.0 μM and 10μM, all the cells died. When treated with lower concentrations ofBI847325 (1.0 nM and 10 nM), cell proliferation seemed to be somewhatinhibited and a differentiation-inducing effect was not observed. U0126showed inhibition of cell proliferation at 0.1 μM and 1.0 μM and at 10μM, showed cell cytotoxicity. Furthermore, U0126 did not show any cleardifferentiation-inducing effect at 2.5 μM and thus failed to show anyNSC differentiation-inducing effect at all concentrations tested.

These results reveal that not all previously known MEK1/2 inhibitorseffectively induce NSC differentiation. According to the results ofExample 5, it is clear that MEK1 and MEK2 inhibition is involved ininducing the differentiation of NSC. However, it is thought that thedistinct property of each MEK 1/2 inhibitor affects its NSCdifferentiation-inducing abilities, leading to differences seen inExample 6.

Example 7 NSC Differentiation-Inducing Effect of other MEK1/2 Inhibitorsin the Presence of Cell Cytotoxic Factors

Adult NSC cultured as described in Example 2, Step 1A were treated with10 μM amyloid-beta as described in Example 2, Step 2 to create acytotoxic environment, after which MEK1/2 inhibitors AS703026 (10 μM),AZD8330 (1 μM), PD318088 (1 μM), binimetinib (10 μM), refametinib (1μM), PD0325901 (10 μM), and RO5126766 (10 μM) were added at theconcentration that caused the most differentiation-inducing effect inExample 6 and cultured. For comparison, 0.1 μM trametinib-treated groupand 10 μM cobimetinib (known as a selective inhibitor of MEK1 comparedwith MEK2)-treated group, as well as amyloid-beta non-treated groups foreach of the tested compound were included. Cell morphology was observedby phase-contrast microscopy on the second day of culture and theresults are shown in FIG. 11.

In FIG. 11, the row marked “-” is the mouse adult NSC group that is nottreated with amyloid-beta and the row marked “Aβ1-42” is the grouptreated with 10 μM amyloid-beta. In conditions where cytoxicity iscaused by the treatment of 10 μM amyloid-beta, it was shown that theaddition of AS703026, AZD8330, PD318088, binimetinib, refametinib,PD0325901, and RO5126766, at each of the optimal concentration thatinduces the most differentiation, provided cell protection and inducedthe differentiation of NSC. In contrast, the addition of cobimetinib, aninhibitor known to be more selective to MEK1 than MEK2, did not inducethe differentiation of adult NSC even at a high concentration of 10 μM,regardless of whether or not amyloid-beta was added.

Example 8 Detection of an Increase in the Number of Neurons in theAlzheimer's Disease Mouse Model

Through these previous experiments, it was shown that among thecompounds that suppress both MEK1 and MEK2, certain compounds induce thedifferentiation of NSC into neurons and protect NSC and neurons againstamyloid-beta, trametinib, in particular, showing a powerful effect. Toconfirm this finding in the neurodegenerative disease mouse model aswell, the neuro-regeneration and therapeutic effect of trametinib wasexamined using the 5XFAD mouse, an animal model that shows symptoms ofAD which is the most common form of neurodegenerative disease. The 5XFADmouse displays neuronal pathologies, the degeneration and cell death ofneurons, especially in the somatosenory cortical layer 5 and subiculumof the brain (Oakley et al. (2006) Intraneuronal beta-amyloidaggregates, neurodegeneration, and neuron loss in transgenic mice withfive familial Alzheimer's disease mutations: potential factors inamyloid plaque formation. J Neurosci. 26(40):10129-10140).

Trametinib was administered orally to the 5XFAD (B6SJL-Tg(APPSwF1Lon,PSEN1*M146L*L286V)6799Vas/Mmjax) AD model mice at 12 monthsof age daily for 28 consecutive days at a dose of 0.1 mg/kg and 1.0mg/kg, whereas vehicle (4% DMSO+Corn oil) was administered to thecontrol group mice in the same method (7 mice/group). For the BrdUstaining to be performed later, 50 mg/kg of BrdU (Sigma, cat#. B5002)was added to the daily dose for the last 5 days. The mouse was thenanesthetized and perfused with PBS for the extraction of the brain. Ofthe brains extracted from 3 mice of each group, half of the brain tissue(hemispheres) was immediately stored in the deep freezer for westernblotting and ELISA experiments to be performed later. The other half ofthe hemispheres plus another 3 extracted mice brains per group wereplaced in 10% formalin solution at 4° C. for 1 day, which was thenfollowed with the proceeding steps to allow good penetration of paraffininto the brain tissue. The brain tissues were immersed sequentially in70%, 80%, 95%, 100% alcohol for 1 hour each for dehydration, thenimmersed in xylene 3 times for 1 hour each for clearing, and embedded inparaffin by placing in liquid paraffin 2 times for 1 hour each. Afterthese procedures, the paraffin-embedded brain tissue (paraffin block)was cut into 5 μm sections, mounted on slides, and stored at roomtemperature. Prior to immunohistochemical staining, the tissues on theslides were rehydrated by sequentially immersing in xylene, 100%, 90%,80%, 70%, 50% alcohol,and then water for 5 minutes each. After placingin sodium citrate (10 mM, pH 6) (Sigma, S4641) buffer, antigen retrievalprocess was performed at 120° C. for 15 minutes, blocked with 10% BSA(Bovine serum albumin), and incubated with antibodies against theneuronal marker NeuN (Cell signaling, cat#. 24307) at 4° C. for 1 day.The next day, the slides were incubated with anti-rabbit antibodies(Vector lab, cat#. PI-1000) at room temperature for 1 hour and thenstained with DAB staining for the analysis of the neuronal distributionin the brain.

Since the 5XFAD mouse is known to have extensive neuronal damage in thecerebral cortex layer 5 and hippocampal subiculum, these regions of thebrain were examined first.

FIG. 12 is the result of the analysis of the sagittal sections of thesomatosensory cortex in the cerebral cortex. As shown in FIG. 12a , inthe vehicle (4% DMSO+corn oil)-administered 5XFAD mouse (control, firstleft picture), the number of NeuN (positive) stained cells havedecreased due to considerable damage of neurons in the cerebral cortexlayer 5. In comparison, 0.1 mg/kg and 1.0 mg/kg trametinib-administered5XFAD mouse showed a significant increase in the number of neuronsstained with NeuN. FIG. 12b indicates the number of NeuN stained cellscounted and represented as the percentage of the number of cells perunit area in the somatosensory cortex layer 5 region. Area samples weretaken from 3 areas per mouse, 3 mice per group, so the number of cellscounted was from a total of 9 areas. The percentage of the number ofNeuN stained cells in the trametinib-administered group compared withthe vehicle-administered group was calculated and shown.

FIG. 13 is the result of the analysis of the coronal sections of themotor cortex in the mouse cerebral cortex. As shown in FIG. 13a , thevehicle-administered 5XFAD mouse (control) showed extensive neuronaldamage in the motor cortex layer 5 with a decreased number of NeuNstained neurons, while the trametinib- group again showed a significantincrease in the number of neurons, as with the results of thesomatosensory cortex. FIG. 13b indicates the number of NeuN stainedcells counted and represented as the percentage of the number of cellsper unit area in the motor cortex layer 5 region. Area samples weretaken from 6 areas per mouse, 3 mice per group, so the number of cellscounted was from a total of 18 areas. The percentage of the number ofNeuN stained cells in the trametinib-administered group compared withthe vehicle-administered group was calculated and shown.

FIG. 14 is the result of the analysis of the sagittal sections of thesubiculum in the mouse hippocampus. As shown in FIG. 14a , thevehicle-administered 5XFAD mouse (control) showed that a significantlysmall number of neurons stained with the neuronal marker NeuN in thehippocampal subiculum, while the trametinib-administered group againshowed a significant increase in the number of neurons, as with theresults of the cerebral cortex. FIG. 14b indicates the number of NeuNstained cells counted and represented as the percentage of the number ofcells per unit area in the dotted area of the hippocampal subiculumshown in FIG. 14a . Area samples were taken from 3 areas per mouse, 3mice per group, so the number of cells counted was from a total of 9areas. The percentage of the number of NeuN stained cells in thetrametinib-administered group compared with the vehicle-administeredgroup was calculated and shown. Through the above experiments, it wasshown that trametinib has the effect of increasing the number of neuronsin the cerebral cortex layer 5 and hippocampal subiculum of the 5XFADmouse.

Example 9 Detection of Neurogenesis in the Alzheimer's Disease MouseModel

In order to determine if the increase in the number of neurons in thecerebral cortex layer 5 and hippocampal subiculum of thetrametinib-administered 5XFAD mouse as shown in Example 8 was due to theneurogenesis effect of trametinib, immunohistochemical analysis wasperformed with various cell markers that appear throughout the processof NSC to neuron differentiation.

DCX (doublecortin), a protein expressed in neural precursor cells, isexpressed mainly in migrating or differentiating neurons and indicatesthat the cell is an immature neuron in the process of neurogenesis. Tuj1(neuron-specific class 1110 tubulin), a protein expressed in activelydividing neural precursor cells or newly generated immature postmitoticneurons, indicates that the cell is a neuron in the process ofneurogenesis. Therefore, by detecting the presence of DCX or Tuj1 byimmunohistochemical staining, it can be determined that neurogenesisoccurs through the differentiation of NSC into neurons.

BrdU (5-Bromodeoxycytidine), an analog of the nucleobase thymidine,replaces thymidine during DNA synthesis in a diving cell, allowing thedetection of dividing cells during neurogenesis by immunohistochemicalstaining.

Example 9-1 Detection of Tuj1 Expression in the Somatosensory Cortex ofthe Cerebrum

Anti-Tuj1 antibodies were added to the brain tissue slides of 5XFADmouse in Example 8 and incubated at 4° C. for 1 day, after which thetissue slides were fluorescently stained by incubating with Fluoresceinisothiocyanate (FITC)-secondary antibodies (Invitrogen, cat#. A21121) atroom temperature for 1 hour. The fluorescent microscopy image of thesomatosensory cortex of the cerebral cortex is shown in FIG. 15. In FIG.15, the areas marked with arrows (→) indicate cells stained with Tuj1and the areas marked with arrowheads (▾) indicate plaques formed byamyloid-beta aggregation. Plaques were present in both vehicle- treatedand trametinib-treated groups. However, the 0.1 mg/kg trametinib-treatedgroup, in particular, showed a significant increase in the number ofcells stained with Tuj1 compared with the vehicle-treated group, despitesimilar levels of amyloid-beta plaques present in the samples.

Example 9-2 Detection of Niss1, NeuN, and DCX Expression in theHippocampal Dentate Gyrus

When neurogenesis is activated in the subgranular zone (SGZ) of thedentate gyrus, asymmetric cell division takes place and as a result,Type 2 cells are generated in the very beginning. Type 2 cells have asmall soma with an atypical nucleus, are short and horizontallyoriented, and express nestin or Dcx. Type 3 cells are cells that haveundergone further differentiation from Type 2 cells and are also calledthe neuroblast. Type 3 cells are cells in the early stage ofdifferentiation in the neuronal, not glial cell lineage. Type 3 cellsare situated closer towards the granular layer from the subgranular zoneof the dentate gyrus and unlike Type 2 cells, have changed from thehorizontally oriented to the vertically oriented shape. The fact thatType 2 and Type 3 cells are present in the subgranular zone of thedentate gyrus indicates that neurogenesis is taking place.

Niss1 staining, which stains the Niss1 body of the neuron, is a methodthat shows the distribution and condition of neurons in the brain. Thebrain tissues on the slides of Example 8 were rehydrated by sequentiallyimmersing in xylene, 100%, 90%, 80%, 70%, 50% alcohol, and then waterfor 5 minutes each. After placing in 0.1% cresyl violet (Sigma, cat#.C5042) solution at room temperature for 15 minutes, they were dehydratedby sequentially immersing in 80%, 90%, 100% alcohol, and xylene.Coverslips were put on the slides and the neurons examined.

NeuN staining was performed by the same method as described in Example 8as was DCX staining, but using anti-DCX antibodies (Santa Cruz, cat#.sc271390) instead of anti-NeuN antibodies.

The results are shown in FIG. 16a . From the Niss1 and NeuN stainings inthe trametinib-administered 5XFAD mouse, it was shown that the number ofcells having the morphology of Type 2 or Type 3 cells that specificallyappear during neurogenesis increased considerably in the subgranularzone (SGZ) and in an area closer to the granular zone than the SGZ inthe dentate gyrus. In addition, immature neurons (marked with arrows (→)in the column labeled “Dcx” in FIG. 16) that are also stained by DCXwere seen to be present, confirming that neurogenesis occurs in thehippocampal dentate gyrus in trametinib-administered mouse.

Example 9-3 BrdU Staining in the Hippocampal Dentate Gyrus Region

Asymmetric division of neural stem cells must proceed for neurogenesisto occur, and this was examined by the following experiment.

Brain tissue slides of BrdU-administered 5XFAD mouse (dailyadministration of 50 mg/kg BrdU for 5 consecutive days before sacrificeas described in Example 8) were rehydrated, placed in 1.5 M HCl(hydrochloric acid), and incubated at 37° C. for 30 minutes. The slideswere blocked with solution containing 0.5% BSA (Bovine serum albumin),0.3% TritonX-100, and 10% normal goat serum and incubated with anti-BrdUantibody (Cell signaling, cat#. 5292) at 4° C. for 1 day.Immunofluorescent staining was performed the next day by incubating theslides with fluorescein isothiocynate (FITC)-secondary antibody at roomtemperature for 1 hour, after which the staining of the hippocampaldentate gyrus region was examined with a fluorescent microscope.

The results are shown in FIG. 16a in the column labeled “BrdU”. Thecells marked by arrowheads (▾) are the BrdU labeled cells. Compared withthe vehicle-administered group, trametinib-administered 5XFAD mouseshowed an increase in the number of cells stained with BrdU in thedentate gyrus. FIG. 16b shows the number of BrdU labeled cells, whichagain showed that the trametinib-administered group showed an increasein the number of cells stained with BrdU. FIG. 16b quantified the numberof cells from a total of 9 areas (3 mice per group and 3 areas permouse) and the average is shown in the graph.

From these results, it is revealed that trametinib induces neurogenesisthrough the differentiation of NSC in the AD mouse model. This suggeststhat not only can trametinib be used as a fundamental treatment for ADbut also for the treatment and prevention of diseases that are caused byneuronal damage or loss in the cerebral cortex, particularly in themotor cortex.

Example 10 Neuroprotective Activity in the AD Mouse Model

In order to determine if trametinib has a neuroprotective effect in thecerebral cortex and hippocampal subiculum of the 5XFAD mouse, theimmunohistochemical TUNEL (terminal deoxynucleotidyl transferase dUTPnick end labeling) assay was performed to detect cell apoptosis. TheTUNEL assay stains the 3′-hydroxyl terminus of fragmented DNA, allowingthe detection of cells undergoing apoptosis in the tissue.

The sagittal brain tissue slides described in Example 8 were rehydratedand stained with the TUNEL assay kit (Promega, Wis., USA, cat#. G3250).Specifically, the brain tissue slides were permeabilized with 20 μg/mlproteinase K solution for 10 minutes, incubated with equilibrationbuffer for 10 minutes, and then incubated with TdT solution at 37° C.for 1 hour. The staining of the somatosensory cortex and subiculum area,areas known to show significant cell death in 5XFAD mouse, wereobserved. TUNEL assay was also performed on the tissue slides of normaladult mouse brain (as control) to confirm that staining was properlydone.

The results are shown in FIG. 17. Green fluorescence staining was notobserved in normal mouse (marked “Normal mouse” in FIG. 17) becauseapoptosis did not occur. However, green fluorescence was observed inmany of the cells in the somatosensory cortex (row marked “cortex” inFIG. 17) and subiculum (row marked “subiculum” in FIG. 17) of the 5XFADmouse. In FIG. 17, stained cells were marked with arrows (→) in thesubiculum; in the somatosensory cortex, no separate marking was done dueto many cells being stained. In the case of trametinib- administered5XFAD mouse, the number of TUNEL stained cells in the somatosensorycortex and subiculum was significantly lower in comparison with thevehicle-administered group.

These results demonstrate that trametinib exerts a protective effectagainst neuron death in the AD mouse model.

Example 11 Cerebellar Purkinje Cell Protection in the AD Mouse Model

Brain tissue slides (of 5XFAD mouse) described in Example 8 wereincubated with anti-Tuj1 and anti-calbindin antibodies (Cell signaling,cat#. 13176) at 4° C. for 1 day and were immunofluorescence stained withfluorescein isothiocyantate (FITC)-secondary antibodies orrhodamine-secondary antibodies at room temperature for 1 hour. Theimmunofluorescence image of the Purkinje cell layer is shown in FIG. 18.Two slides for Tuj1 staining and three for calbindin staining are shownfor each treatment group.

As shown in FIG. 18, the Purkinje cells of the vehicle-treated groupexhibited thin protruding axons that show a pattern of being cut off inthe middle. In contrast, the trametinib-administered group, particularlythe 0.1 mg/kg trametinib-treated group, exhibited Purkinje cells withincreased axon arborization or at least with preserved axon structurewhen compared with the vehicle treated control.

The cerebellum is known to play an important role in the integration ofsensory recognition and the regulation and control of motor movements.The most striking cells in the cerebellum, Purkinje cells are one of thelargest cells in the brain, and through their elaborate axonarborization, they form synapses with each other and extend deep intothe nucleus of the cerebellum to regulate and control motor muscle. Theabove experimental results indicate that trametinib protects thePurkinje cells and increases arborization of the axons in thecerebellum, possibly providing treatment to diseases such as cerebellarataxia that are caused by the loss or damage of Purkinje cells in thecerebellum.

Example 12 Trametinib's Inhibition of MEK Activity in the AD Mouse Model

Since neurodegenerative disease treatment drugs act on the centralnervous system, the question of whether or not they can cross the bloodbrain barrier to act on the brain is important. Among the MEK 1/2inhibitors, compounds such as AS703026 are known to effectively crossthe BBB and inhibit MEK and decrease the expression of phosphorylatedERK in the mouse brain (Shaw et al. (2012) Evaluation of brainpharmacokinetics as a potential differentiation factor for the MEKinhibitors, MSC2015103 and pimasertib. Abstract LB-456, AmericanAssociation for Cancer Research Annual Meeting, Chicago, Ill.). Toconfirm that the MEK1/2 inhibitor trametinib enters the brain to producethe above experimental results when PO administered to 5XFAD mouse, theexpression level of pERK was measured in the brain tissue.

The 5XFAD mouse brain hemispheres (3 mice per group) from Example 8stored in a deep freezer were placed in liquid nitrogen and ground in amortar filled with liquid nitrogen. The powder was divided into 6 parts,put into new tubes, and placed back into the deep freezer. One of thetubes was taken out and used for western blotting as described inExample 5-2. The powder was carefully suspended with a pipette in RIPAbuffer, incubated on ice for 10 minutes, centrifuged at 13000 rpm, 4°C., and the supernatant was collected. After measuring the proteinconcentration, sample buffer (0.25 M Tris-HCl pH6.8, 0.05% SDS, 50%glycerol, 0.25 M DTT, 0.5 mg/ml BPB) was added, boiled at 100° C. for 10minutes, and stored at −20° C. 10 μg of protein sample was loaded onto a10% SDS-PAGE gel, subjected to electrophoresis, transferred onto anitrocellulose membrane, and blocked with 5% skim milk at roomtemperature for 1 hour. Western blotting was performed using anti-pERK(Cell signaling, cat#. 4370) and anti-ERK antibodies in tris bufferedsaline (TBS) with 0.1% Tween 20, which were incubated at roomtemperature for 1 hour and subsequently followed with incubation withhorseradish peroxidase-conjugated secondary antibodies at roomtemperature for 1 hour. The protein bands were detected with aphotosensitive imaging system (FIG. 19a ). In order to quantify thechange in pERK expression, the expression levels of pERK and ERK weremeasured by densitometry, and the expression level of pERK wasnormalized against the expression level of ERK. The normalizedexpression level of pERK in trametinib-treated group versus thevehicle-treated group is shown in FIG. 19 b.

As shown in FIG. 19, the protein level of pERK in the brain of 0.1 mg/kgand 1.0 mg/kg trametinib-administered mouse is considerably lower thanthat of the vehicle group.

This finding indicates that the PO administration of trametinib resultsin the delivery of trametinib to the brain to subsequently inhibit MEKactivity and decrease the expression of pERK, through which neurogenesisand neuroprotection appears to be manifested.

Example 13 Decrease in Amyloid-Beta Deposition in the AD Mouse Model

Since the main pathological feature of AD is the deposition of Aβ, theability of trametinib to decrease the deposition of Aβ was examined.Using the ground powder of 5XFAD mouse brain hemispheres obtained inExample 12, the amount of Aβ(1-40) and Aβ(1-42) was quantified by ELISA(enzyme-linked immunosorbent assay). The assay was performed using anELISA kit (Invitrogen, Mass., cat#. KHB3442) as follows: First, themouse brain powder was carefully suspended with a pipette in 5 Mguanidine-HCl solution, centrifuged at 16000×g (rpm), 4° C., and thesupernatant was collected. After measuring the protein concentration,dilution buffer was added to obtain 30˜50 μg of protein in 100 μlsolution. 100 μl each of anti-Aβ(1-40) and Aβ(1-42) antibodies wereadded to the 96-well plates, incubated at room temperature for 2 hours,then removed and washed 4 times with wash buffer. 100 μl each ofHRP-conjugated secondary antibodies was added and incubated at roomtemperature for 30 minutes. The solution was then removed and washedagain 4 times with wash buffer. 100 μl of the protein prepared from themouse brain powder was added to the wells, incubated in the dark for 30minutes, and 100 μl of the stop solution added to terminate thereaction. Then, the chemiluminiscence reaction was measured at 450 nmwith an ELISA plate reader. The absorbance was converted in reference tothe standard concentration and the concentration of each protein wasdetermined. The amount of Aβ(1-40) and Aβ(1-42) in reference to thetotal amount of protein (30˜50 μg) was calculated, and then the amountof Aβ(1-42) in reference to the amount of Aβ(1-40) was calculated. Theaverages of the 3 mouse measurements for each group were obtained andare shown in FIG. 20. As shown in FIG. 20, the amount ofAβ(1-42)/Aβ(1-40) decreased in the trametinib-treated group comparedwith the vehicle-treated group.

This finding indicates that in the AD animal model, trametinib decreasedthe amount of Aβ, particularly the Aβ(1-42) form that has a strongtendency to form toxic oligomers or aggregates, and in this way, couldprovide protection to neurons.

What is claimed is:
 1. A method of treating a neurodegenerative disease, comprising the step of: administering trametinib to a patient diagnosed with the neurodegenerative disease, wherein the neurodegenerative disease is selected from the group consisting of: dementia, vascular dementia, senile dementia, frontotemporal dementia, Lewy body dementia, Parkinson's disease, multiple system atrophy, corticobasal degeneration, progressive supranuclear palsy, Huntington's disease, amyotrophic lateral sclerosis (ALS or Lou-Gehrig's disease), primary lateral sclerosis, progressive bulbar palsy (PBP), progressive muscular atrophy (PMA), pseudobulbar palsy, hereditary spastic paraplegia (HSP), cerebellar ataxia, Creutzfeldt-Jakob disease, multiple sclerosis, and Guillain-Barré syndrome.
 2. The method of claim 1, wherein the neurodegenerative disease is vascular dementia.
 3. The method of claim 1, wherein the neurodegenerative disease is amyotrophic lateral sclerosis (ALS or Lou-Gehrig's disease).
 4. The method of claim 1, wherein the neurodegenerative disease is Huntington's disease.
 5. The method of claim 1, wherein trametinib is administered in an amount sufficient to reduce a symptom associated with the neurodegenerative disease.
 6. The method of claim 1, wherein trametinib is administered in an amount sufficient to induce neuro-regeneration.
 7. The method of claim 6, wherein the amount is sufficient to induce differentiation of a neural stem cell into a neuron in the patient.
 8. The method of claim 7, wherein the neuron differentiated from the neural stem cell is selected from the group consisting of: a dopaminergic neuron, a GABAergic neuron, a motor neuron, and a cholinergic neuron.
 9. The method of claim 1, wherein trametinib is administered in an amount of between 0.1 mg and 2 mg once daily.
 10. The method of claim 9, wherein trametinib is administered in an amount of not more than 1 mg once daily.
 11. The method of claim 10, wherein trametinib is administered in an amount of not more than 0.5 mg once daily. 